fs/btrfs/scrub.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2011, 2012 STRATO.  All rights reserved.
   4  */
   5
   6 #include <linux/blkdev.h>
   7 #include <linux/ratelimit.h>
   8 #include <linux/sched/mm.h>
   9 #include <crypto/hash.h>
  10 #include "ctree.h"
  11 #include "volumes.h"
  12 #include "disk-io.h"
  13 #include "ordered-data.h"
  14 #include "transaction.h"
  15 #include "backref.h"
  16 #include "extent_io.h"
  17 #include "dev-replace.h"
  18 #include "check-integrity.h"
  19 #include "rcu-string.h"
  20 #include "raid56.h"
  21 #include "block-group.h"
  22
  23 /*
  24  * This is only the first step towards a full-features scrub. It reads all
  25  * extent and super block and verifies the checksums. In case a bad checksum
  26  * is found or the extent cannot be read, good data will be written back if
  27  * any can be found.
  28  *
  29  * Future enhancements:
  30  *  - In case an unrepairable extent is encountered, track which files are
  31  *    affected and report them
  32  *  - track and record media errors, throw out bad devices
  33  *  - add a mode to also read unallocated space
  34  */
  35
  36 struct scrub_block;
  37 struct scrub_ctx;
  38
  39 /*
  40  * the following three values only influence the performance.
  41  * The last one configures the number of parallel and outstanding I/O
  42  * operations. The first two values configure an upper limit for the number
  43  * of (dynamically allocated) pages that are added to a bio.
  44  */
  45 #define SCRUB_PAGES_PER_RD_BIO  32      /* 128k per bio */
  46 #define SCRUB_PAGES_PER_WR_BIO  32      /* 128k per bio */
  47 #define SCRUB_BIOS_PER_SCTX     64      /* 8MB per device in flight */
  48
  49 /*
  50  * the following value times PAGE_SIZE needs to be large enough to match the
  51  * largest node/leaf/sector size that shall be supported.
  52  * Values larger than BTRFS_STRIPE_LEN are not supported.
  53  */
  54 #define SCRUB_MAX_PAGES_PER_BLOCK       16      /* 64k per node/leaf/sector */
  55
  56 struct scrub_recover {
  57         refcount_t              refs;
  58         struct btrfs_bio        *bbio;
  59         u64                     map_length;
  60 };
  61
  62 struct scrub_page {
  63         struct scrub_block      *sblock;
  64         struct page             *page;
  65         struct btrfs_device     *dev;
  66         struct list_head        list;
  67         u64                     flags;  /* extent flags */
  68         u64                     generation;
  69         u64                     logical;
  70         u64                     physical;
  71         u64                     physical_for_dev_replace;
  72         atomic_t                refs;
  73         struct {
  74                 unsigned int    mirror_num:8;
  75                 unsigned int    have_csum:1;
  76                 unsigned int    io_error:1;
  77         };
  78         u8                      csum[BTRFS_CSUM_SIZE];
  79
  80         struct scrub_recover    *recover;
  81 };
  82
  83 struct scrub_bio {
  84         int                     index;
  85         struct scrub_ctx        *sctx;
  86         struct btrfs_device     *dev;
  87         struct bio              *bio;
  88         blk_status_t            status;
  89         u64                     logical;
  90         u64                     physical;
  91 #if SCRUB_PAGES_PER_WR_BIO >= SCRUB_PAGES_PER_RD_BIO
  92         struct scrub_page       *pagev[SCRUB_PAGES_PER_WR_BIO];
  93 #else
  94         struct scrub_page       *pagev[SCRUB_PAGES_PER_RD_BIO];
  95 #endif
  96         int                     page_count;
  97         int                     next_free;
  98         struct btrfs_work       work;
  99 };
 100
 101 struct scrub_block {
 102         struct scrub_page       *pagev[SCRUB_MAX_PAGES_PER_BLOCK];
 103         int                     page_count;
 104         atomic_t                outstanding_pages;
 105         refcount_t              refs; /* free mem on transition to zero */
 106         struct scrub_ctx        *sctx;
 107         struct scrub_parity     *sparity;
 108         struct {
 109                 unsigned int    header_error:1;
 110                 unsigned int    checksum_error:1;
 111                 unsigned int    no_io_error_seen:1;
 112                 unsigned int    generation_error:1; /* also sets header_error */
 113
 114                 /* The following is for the data used to check parity */
 115                 /* It is for the data with checksum */
 116                 unsigned int    data_corrected:1;
 117         };
 118         struct btrfs_work       work;
 119 };
 120
 121 /* Used for the chunks with parity stripe such RAID5/6 */
 122 struct scrub_parity {
 123         struct scrub_ctx        *sctx;
 124
 125         struct btrfs_device     *scrub_dev;
 126
 127         u64                     logic_start;
 128
 129         u64                     logic_end;
 130
 131         int                     nsectors;
 132
 133         u64                     stripe_len;
 134
 135         refcount_t              refs;
 136
 137         struct list_head        spages;
 138
 139         /* Work of parity check and repair */
 140         struct btrfs_work       work;
 141
 142         /* Mark the parity blocks which have data */
 143         unsigned long           *dbitmap;
 144
 145         /*
 146          * Mark the parity blocks which have data, but errors happen when
 147          * read data or check data
 148          */
 149         unsigned long           *ebitmap;
 150
 151         unsigned long           bitmap[0];
 152 };
 153
 154 struct scrub_ctx {
 155         struct scrub_bio        *bios[SCRUB_BIOS_PER_SCTX];
 156         struct btrfs_fs_info    *fs_info;
 157         int                     first_free;
 158         int                     curr;
 159         atomic_t                bios_in_flight;
 160         atomic_t                workers_pending;
 161         spinlock_t              list_lock;
 162         wait_queue_head_t       list_wait;
 163         u16                     csum_size;
 164         struct list_head        csum_list;
 165         atomic_t                cancel_req;
 166         int                     readonly;
 167         int                     pages_per_rd_bio;
 168
 169         int                     is_dev_replace;
 170
 171         struct scrub_bio        *wr_curr_bio;
 172         struct mutex            wr_lock;
 173         int                     pages_per_wr_bio; /* <= SCRUB_PAGES_PER_WR_BIO */
 174         struct btrfs_device     *wr_tgtdev;
 175         bool                    flush_all_writes;
 176
 177         /*
 178          * statistics
 179          */
 180         struct btrfs_scrub_progress stat;
 181         spinlock_t              stat_lock;
 182
 183         /*
 184          * Use a ref counter to avoid use-after-free issues. Scrub workers
 185          * decrement bios_in_flight and workers_pending and then do a wakeup
 186          * on the list_wait wait queue. We must ensure the main scrub task
 187          * doesn't free the scrub context before or while the workers are
 188          * doing the wakeup() call.
 189          */
 190         refcount_t              refs;
 191 };
 192
 193 struct scrub_warning {
 194         struct btrfs_path       *path;
 195         u64                     extent_item_size;
 196         const char              *errstr;
 197         u64                     physical;
 198         u64                     logical;
 199         struct btrfs_device     *dev;
 200 };
 201
 202 struct full_stripe_lock {
 203         struct rb_node node;
 204         u64 logical;
 205         u64 refs;
 206         struct mutex mutex;
 207 };
 208
 209 static void scrub_pending_bio_inc(struct scrub_ctx *sctx);
 210 static void scrub_pending_bio_dec(struct scrub_ctx *sctx);
 211 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check);
 212 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
 213                                      struct scrub_block *sblocks_for_recheck);
 214 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
 215                                 struct scrub_block *sblock,
 216                                 int retry_failed_mirror);
 217 static void scrub_recheck_block_checksum(struct scrub_block *sblock);
 218 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
 219                                              struct scrub_block *sblock_good);
 220 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
 221                                             struct scrub_block *sblock_good,
 222                                             int page_num, int force_write);
 223 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock);
 224 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
 225                                            int page_num);
 226 static int scrub_checksum_data(struct scrub_block *sblock);
 227 static int scrub_checksum_tree_block(struct scrub_block *sblock);
 228 static int scrub_checksum_super(struct scrub_block *sblock);
 229 static void scrub_block_get(struct scrub_block *sblock);
 230 static void scrub_block_put(struct scrub_block *sblock);
 231 static void scrub_page_get(struct scrub_page *spage);
 232 static void scrub_page_put(struct scrub_page *spage);
 233 static void scrub_parity_get(struct scrub_parity *sparity);
 234 static void scrub_parity_put(struct scrub_parity *sparity);
 235 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
 236                                     struct scrub_page *spage);
 237 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 238                        u64 physical, struct btrfs_device *dev, u64 flags,
 239                        u64 gen, int mirror_num, u8 *csum, int force,
 240                        u64 physical_for_dev_replace);
 241 static void scrub_bio_end_io(struct bio *bio);
 242 static void scrub_bio_end_io_worker(struct btrfs_work *work);
 243 static void scrub_block_complete(struct scrub_block *sblock);
 244 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
 245                                u64 extent_logical, u64 extent_len,
 246                                u64 *extent_physical,
 247                                struct btrfs_device **extent_dev,
 248                                int *extent_mirror_num);
 249 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
 250                                     struct scrub_page *spage);
 251 static void scrub_wr_submit(struct scrub_ctx *sctx);
 252 static void scrub_wr_bio_end_io(struct bio *bio);
 253 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work);
 254 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 255 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
 256 static void scrub_put_ctx(struct scrub_ctx *sctx);
 257
 258 static inline int scrub_is_page_on_raid56(struct scrub_page *page)
 259 {
 260         return page->recover &&
 261                (page->recover->bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK);
 262 }
 263
 264 static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
 265 {
 266         refcount_inc(&sctx->refs);
 267         atomic_inc(&sctx->bios_in_flight);
 268 }
 269
 270 static void scrub_pending_bio_dec(struct scrub_ctx *sctx)
 271 {
 272         atomic_dec(&sctx->bios_in_flight);
 273         wake_up(&sctx->list_wait);
 274         scrub_put_ctx(sctx);
 275 }
 276
 277 static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 278 {
 279         while (atomic_read(&fs_info->scrub_pause_req)) {
 280                 mutex_unlock(&fs_info->scrub_lock);
 281                 wait_event(fs_info->scrub_pause_wait,
 282                    atomic_read(&fs_info->scrub_pause_req) == 0);
 283                 mutex_lock(&fs_info->scrub_lock);
 284         }
 285 }
 286
 287 static void scrub_pause_on(struct btrfs_fs_info *fs_info)
 288 {
 289         atomic_inc(&fs_info->scrubs_paused);
 290         wake_up(&fs_info->scrub_pause_wait);
 291 }
 292
 293 static void scrub_pause_off(struct btrfs_fs_info *fs_info)
 294 {
 295         mutex_lock(&fs_info->scrub_lock);
 296         __scrub_blocked_if_needed(fs_info);
 297         atomic_dec(&fs_info->scrubs_paused);
 298         mutex_unlock(&fs_info->scrub_lock);
 299
 300         wake_up(&fs_info->scrub_pause_wait);
 301 }
 302
 303 static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 304 {
 305         scrub_pause_on(fs_info);
 306         scrub_pause_off(fs_info);
 307 }
 308
 309 /*
 310  * Insert new full stripe lock into full stripe locks tree
 311  *
 312  * Return pointer to existing or newly inserted full_stripe_lock structure if
 313  * everything works well.
 314  * Return ERR_PTR(-ENOMEM) if we failed to allocate memory
 315  *
 316  * NOTE: caller must hold full_stripe_locks_root->lock before calling this
 317  * function
 318  */
 319 static struct full_stripe_lock *insert_full_stripe_lock(
 320                 struct btrfs_full_stripe_locks_tree *locks_root,
 321                 u64 fstripe_logical)
 322 {
 323         struct rb_node **p;
 324         struct rb_node *parent = NULL;
 325         struct full_stripe_lock *entry;
 326         struct full_stripe_lock *ret;
 327
 328         lockdep_assert_held(&locks_root->lock);
 329
 330         p = &locks_root->root.rb_node;
 331         while (*p) {
 332                 parent = *p;
 333                 entry = rb_entry(parent, struct full_stripe_lock, node);
 334                 if (fstripe_logical < entry->logical) {
 335                         p = &(*p)->rb_left;
 336                 } else if (fstripe_logical > entry->logical) {
 337                         p = &(*p)->rb_right;
 338                 } else {
 339                         entry->refs++;
 340                         return entry;
 341                 }
 342         }
 343
 344         /*
 345          * Insert new lock.
 346          */
 347         ret = kmalloc(sizeof(*ret), GFP_KERNEL);
 348         if (!ret)
 349                 return ERR_PTR(-ENOMEM);
 350         ret->logical = fstripe_logical;
 351         ret->refs = 1;
 352         mutex_init(&ret->mutex);
 353
 354         rb_link_node(&ret->node, parent, p);
 355         rb_insert_color(&ret->node, &locks_root->root);
 356         return ret;
 357 }
 358
 359 /*
 360  * Search for a full stripe lock of a block group
 361  *
 362  * Return pointer to existing full stripe lock if found
 363  * Return NULL if not found
 364  */
 365 static struct full_stripe_lock *search_full_stripe_lock(
 366                 struct btrfs_full_stripe_locks_tree *locks_root,
 367                 u64 fstripe_logical)
 368 {
 369         struct rb_node *node;
 370         struct full_stripe_lock *entry;
 371
 372         lockdep_assert_held(&locks_root->lock);
 373
 374         node = locks_root->root.rb_node;
 375         while (node) {
 376                 entry = rb_entry(node, struct full_stripe_lock, node);
 377                 if (fstripe_logical < entry->logical)
 378                         node = node->rb_left;
 379                 else if (fstripe_logical > entry->logical)
 380                         node = node->rb_right;
 381                 else
 382                         return entry;
 383         }
 384         return NULL;
 385 }
 386
 387 /*
 388  * Helper to get full stripe logical from a normal bytenr.
 389  *
 390  * Caller must ensure @cache is a RAID56 block group.
 391  */
 392 static u64 get_full_stripe_logical(struct btrfs_block_group *cache, u64 bytenr)
 393 {
 394         u64 ret;
 395
 396         /*
 397          * Due to chunk item size limit, full stripe length should not be
 398          * larger than U32_MAX. Just a sanity check here.
 399          */
 400         WARN_ON_ONCE(cache->full_stripe_len >= U32_MAX);
 401
 402         /*
 403          * round_down() can only handle power of 2, while RAID56 full
 404          * stripe length can be 64KiB * n, so we need to manually round down.
 405          */
 406         ret = div64_u64(bytenr - cache->start, cache->full_stripe_len) *
 407                         cache->full_stripe_len + cache->start;
 408         return ret;
 409 }
 410
 411 /*
 412  * Lock a full stripe to avoid concurrency of recovery and read
 413  *
 414  * It's only used for profiles with parities (RAID5/6), for other profiles it
 415  * does nothing.
 416  *
 417  * Return 0 if we locked full stripe covering @bytenr, with a mutex held.
 418  * So caller must call unlock_full_stripe() at the same context.
 419  *
 420  * Return <0 if encounters error.
 421  */
 422 static int lock_full_stripe(struct btrfs_fs_info *fs_info, u64 bytenr,
 423                             bool *locked_ret)
 424 {
 425         struct btrfs_block_group *bg_cache;
 426         struct btrfs_full_stripe_locks_tree *locks_root;
 427         struct full_stripe_lock *existing;
 428         u64 fstripe_start;
 429         int ret = 0;
 430
 431         *locked_ret = false;
 432         bg_cache = btrfs_lookup_block_group(fs_info, bytenr);
 433         if (!bg_cache) {
 434                 ASSERT(0);
 435                 return -ENOENT;
 436         }
 437
 438         /* Profiles not based on parity don't need full stripe lock */
 439         if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_RAID56_MASK))
 440                 goto out;
 441         locks_root = &bg_cache->full_stripe_locks_root;
 442
 443         fstripe_start = get_full_stripe_logical(bg_cache, bytenr);
 444
 445         /* Now insert the full stripe lock */
 446         mutex_lock(&locks_root->lock);
 447         existing = insert_full_stripe_lock(locks_root, fstripe_start);
 448         mutex_unlock(&locks_root->lock);
 449         if (IS_ERR(existing)) {
 450                 ret = PTR_ERR(existing);
 451                 goto out;
 452         }
 453         mutex_lock(&existing->mutex);
 454         *locked_ret = true;
 455 out:
 456         btrfs_put_block_group(bg_cache);
 457         return ret;
 458 }
 459
 460 /*
 461  * Unlock a full stripe.
 462  *
 463  * NOTE: Caller must ensure it's the same context calling corresponding
 464  * lock_full_stripe().
 465  *
 466  * Return 0 if we unlock full stripe without problem.
 467  * Return <0 for error
 468  */
 469 static int unlock_full_stripe(struct btrfs_fs_info *fs_info, u64 bytenr,
 470                               bool locked)
 471 {
 472         struct btrfs_block_group *bg_cache;
 473         struct btrfs_full_stripe_locks_tree *locks_root;
 474         struct full_stripe_lock *fstripe_lock;
 475         u64 fstripe_start;
 476         bool freeit = false;
 477         int ret = 0;
 478
 479         /* If we didn't acquire full stripe lock, no need to continue */
 480         if (!locked)
 481                 return 0;
 482
 483         bg_cache = btrfs_lookup_block_group(fs_info, bytenr);
 484         if (!bg_cache) {
 485                 ASSERT(0);
 486                 return -ENOENT;
 487         }
 488         if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_RAID56_MASK))
 489                 goto out;
 490
 491         locks_root = &bg_cache->full_stripe_locks_root;
 492         fstripe_start = get_full_stripe_logical(bg_cache, bytenr);
 493
 494         mutex_lock(&locks_root->lock);
 495         fstripe_lock = search_full_stripe_lock(locks_root, fstripe_start);
 496         /* Unpaired unlock_full_stripe() detected */
 497         if (!fstripe_lock) {
 498                 WARN_ON(1);
 499                 ret = -ENOENT;
 500                 mutex_unlock(&locks_root->lock);
 501                 goto out;
 502         }
 503
 504         if (fstripe_lock->refs == 0) {
 505                 WARN_ON(1);
 506                 btrfs_warn(fs_info, "full stripe lock at %llu refcount underflow",
 507                         fstripe_lock->logical);
 508         } else {
 509                 fstripe_lock->refs--;
 510         }
 511
 512         if (fstripe_lock->refs == 0) {
 513                 rb_erase(&fstripe_lock->node, &locks_root->root);
 514                 freeit = true;
 515         }
 516         mutex_unlock(&locks_root->lock);
 517
 518         mutex_unlock(&fstripe_lock->mutex);
 519         if (freeit)
 520                 kfree(fstripe_lock);
 521 out:
 522         btrfs_put_block_group(bg_cache);
 523         return ret;
 524 }
 525
 526 static void scrub_free_csums(struct scrub_ctx *sctx)
 527 {
 528         while (!list_empty(&sctx->csum_list)) {
 529                 struct btrfs_ordered_sum *sum;
 530                 sum = list_first_entry(&sctx->csum_list,
 531                                        struct btrfs_ordered_sum, list);
 532                 list_del(&sum->list);
 533                 kfree(sum);
 534         }
 535 }
 536
 537 static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
 538 {
 539         int i;
 540
 541         if (!sctx)
 542                 return;
 543
 544         /* this can happen when scrub is cancelled */
 545         if (sctx->curr != -1) {
 546                 struct scrub_bio *sbio = sctx->bios[sctx->curr];
 547
 548                 for (i = 0; i < sbio->page_count; i++) {
 549                         WARN_ON(!sbio->pagev[i]->page);
 550                         scrub_block_put(sbio->pagev[i]->sblock);
 551                 }
 552                 bio_put(sbio->bio);
 553         }
 554
 555         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 556                 struct scrub_bio *sbio = sctx->bios[i];
 557
 558                 if (!sbio)
 559                         break;
 560                 kfree(sbio);
 561         }
 562
 563         kfree(sctx->wr_curr_bio);
 564         scrub_free_csums(sctx);
 565         kfree(sctx);
 566 }
 567
 568 static void scrub_put_ctx(struct scrub_ctx *sctx)
 569 {
 570         if (refcount_dec_and_test(&sctx->refs))
 571                 scrub_free_ctx(sctx);
 572 }
 573
 574 static noinline_for_stack struct scrub_ctx *scrub_setup_ctx(
 575                 struct btrfs_fs_info *fs_info, int is_dev_replace)
 576 {
 577         struct scrub_ctx *sctx;
 578         int             i;
 579
 580         sctx = kzalloc(sizeof(*sctx), GFP_KERNEL);
 581         if (!sctx)
 582                 goto nomem;
 583         refcount_set(&sctx->refs, 1);
 584         sctx->is_dev_replace = is_dev_replace;
 585         sctx->pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
 586         sctx->curr = -1;
 587         sctx->fs_info = fs_info;
 588         INIT_LIST_HEAD(&sctx->csum_list);
 589         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
 590                 struct scrub_bio *sbio;
 591
 592                 sbio = kzalloc(sizeof(*sbio), GFP_KERNEL);
 593                 if (!sbio)
 594                         goto nomem;
 595                 sctx->bios[i] = sbio;
 596
 597                 sbio->index = i;
 598                 sbio->sctx = sctx;
 599                 sbio->page_count = 0;
 600                 btrfs_init_work(&sbio->work, scrub_bio_end_io_worker, NULL,
 601                                 NULL);
 602
 603                 if (i != SCRUB_BIOS_PER_SCTX - 1)
 604                         sctx->bios[i]->next_free = i + 1;
 605                 else
 606                         sctx->bios[i]->next_free = -1;
 607         }
 608         sctx->first_free = 0;
 609         atomic_set(&sctx->bios_in_flight, 0);
 610         atomic_set(&sctx->workers_pending, 0);
 611         atomic_set(&sctx->cancel_req, 0);
 612         sctx->csum_size = btrfs_super_csum_size(fs_info->super_copy);
 613
 614         spin_lock_init(&sctx->list_lock);
 615         spin_lock_init(&sctx->stat_lock);
 616         init_waitqueue_head(&sctx->list_wait);
 617
 618         WARN_ON(sctx->wr_curr_bio != NULL);
 619         mutex_init(&sctx->wr_lock);
 620         sctx->wr_curr_bio = NULL;
 621         if (is_dev_replace) {
 622                 WARN_ON(!fs_info->dev_replace.tgtdev);
 623                 sctx->pages_per_wr_bio = SCRUB_PAGES_PER_WR_BIO;
 624                 sctx->wr_tgtdev = fs_info->dev_replace.tgtdev;
 625                 sctx->flush_all_writes = false;
 626         }
 627
 628         return sctx;
 629
 630 nomem:
 631         scrub_free_ctx(sctx);
 632         return ERR_PTR(-ENOMEM);
 633 }
 634
 635 static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
 636                                      void *warn_ctx)
 637 {
 638         u64 isize;
 639         u32 nlink;
 640         int ret;
 641         int i;
 642         unsigned nofs_flag;
 643         struct extent_buffer *eb;
 644         struct btrfs_inode_item *inode_item;
 645         struct scrub_warning *swarn = warn_ctx;
 646         struct btrfs_fs_info *fs_info = swarn->dev->fs_info;
 647         struct inode_fs_paths *ipath = NULL;
 648         struct btrfs_root *local_root;
 649         struct btrfs_key root_key;
 650         struct btrfs_key key;
 651
 652         root_key.objectid = root;
 653         root_key.type = BTRFS_ROOT_ITEM_KEY;
 654         root_key.offset = (u64)-1;
 655         local_root = btrfs_read_fs_root_no_name(fs_info, &root_key);
 656         if (IS_ERR(local_root)) {
 657                 ret = PTR_ERR(local_root);
 658                 goto err;
 659         }
 660
 661         /*
 662          * this makes the path point to (inum INODE_ITEM ioff)
 663          */
 664         key.objectid = inum;
 665         key.type = BTRFS_INODE_ITEM_KEY;
 666         key.offset = 0;
 667
 668         ret = btrfs_search_slot(NULL, local_root, &key, swarn->path, 0, 0);
 669         if (ret) {
 670                 btrfs_release_path(swarn->path);
 671                 goto err;
 672         }
 673
 674         eb = swarn->path->nodes[0];
 675         inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
 676                                         struct btrfs_inode_item);
 677         isize = btrfs_inode_size(eb, inode_item);
 678         nlink = btrfs_inode_nlink(eb, inode_item);
 679         btrfs_release_path(swarn->path);
 680
 681         /*
 682          * init_path might indirectly call vmalloc, or use GFP_KERNEL. Scrub
 683          * uses GFP_NOFS in this context, so we keep it consistent but it does
 684          * not seem to be strictly necessary.
 685          */
 686         nofs_flag = memalloc_nofs_save();
 687         ipath = init_ipath(4096, local_root, swarn->path);
 688         memalloc_nofs_restore(nofs_flag);
 689         if (IS_ERR(ipath)) {
 690                 ret = PTR_ERR(ipath);
 691                 ipath = NULL;
 692                 goto err;
 693         }
 694         ret = paths_from_inode(inum, ipath);
 695
 696         if (ret < 0)
 697                 goto err;
 698
 699         /*
 700          * we deliberately ignore the bit ipath might have been too small to
 701          * hold all of the paths here
 702          */
 703         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
 704                 btrfs_warn_in_rcu(fs_info,
 705 "%s at logical %llu on dev %s, physical %llu, root %llu, inode %llu, offset %llu, length %llu, links %u (path: %s)",
 706                                   swarn->errstr, swarn->logical,
 707                                   rcu_str_deref(swarn->dev->name),
 708                                   swarn->physical,
 709                                   root, inum, offset,
 710                                   min(isize - offset, (u64)PAGE_SIZE), nlink,
 711                                   (char *)(unsigned long)ipath->fspath->val[i]);
 712
 713         free_ipath(ipath);
 714         return 0;
 715
 716 err:
 717         btrfs_warn_in_rcu(fs_info,
 718                           "%s at logical %llu on dev %s, physical %llu, root %llu, inode %llu, offset %llu: path resolving failed with ret=%d",
 719                           swarn->errstr, swarn->logical,
 720                           rcu_str_deref(swarn->dev->name),
 721                           swarn->physical,
 722                           root, inum, offset, ret);
 723
 724         free_ipath(ipath);
 725         return 0;
 726 }
 727
 728 static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
 729 {
 730         struct btrfs_device *dev;
 731         struct btrfs_fs_info *fs_info;
 732         struct btrfs_path *path;
 733         struct btrfs_key found_key;
 734         struct extent_buffer *eb;
 735         struct btrfs_extent_item *ei;
 736         struct scrub_warning swarn;
 737         unsigned long ptr = 0;
 738         u64 extent_item_pos;
 739         u64 flags = 0;
 740         u64 ref_root;
 741         u32 item_size;
 742         u8 ref_level = 0;
 743         int ret;
 744
 745         WARN_ON(sblock->page_count < 1);
 746         dev = sblock->pagev[0]->dev;
 747         fs_info = sblock->sctx->fs_info;
 748
 749         path = btrfs_alloc_path();
 750         if (!path)
 751                 return;
 752
 753         swarn.physical = sblock->pagev[0]->physical;
 754         swarn.logical = sblock->pagev[0]->logical;
 755         swarn.errstr = errstr;
 756         swarn.dev = NULL;
 757
 758         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key,
 759                                   &flags);
 760         if (ret < 0)
 761                 goto out;
 762
 763         extent_item_pos = swarn.logical - found_key.objectid;
 764         swarn.extent_item_size = found_key.offset;
 765
 766         eb = path->nodes[0];
 767         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
 768         item_size = btrfs_item_size_nr(eb, path->slots[0]);
 769
 770         if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 771                 do {
 772                         ret = tree_backref_for_extent(&ptr, eb, &found_key, ei,
 773                                                       item_size, &ref_root,
 774                                                       &ref_level);
 775                         btrfs_warn_in_rcu(fs_info,
 776 "%s at logical %llu on dev %s, physical %llu: metadata %s (level %d) in tree %llu",
 777                                 errstr, swarn.logical,
 778                                 rcu_str_deref(dev->name),
 779                                 swarn.physical,
 780                                 ref_level ? "node" : "leaf",
 781                                 ret < 0 ? -1 : ref_level,
 782                                 ret < 0 ? -1 : ref_root);
 783                 } while (ret != 1);
 784                 btrfs_release_path(path);
 785         } else {
 786                 btrfs_release_path(path);
 787                 swarn.path = path;
 788                 swarn.dev = dev;
 789                 iterate_extent_inodes(fs_info, found_key.objectid,
 790                                         extent_item_pos, 1,
 791                                         scrub_print_warning_inode, &swarn, false);
 792         }
 793
 794 out:
 795         btrfs_free_path(path);
 796 }
 797
 798 static inline void scrub_get_recover(struct scrub_recover *recover)
 799 {
 800         refcount_inc(&recover->refs);
 801 }
 802
 803 static inline void scrub_put_recover(struct btrfs_fs_info *fs_info,
 804                                      struct scrub_recover *recover)
 805 {
 806         if (refcount_dec_and_test(&recover->refs)) {
 807                 btrfs_bio_counter_dec(fs_info);
 808                 btrfs_put_bbio(recover->bbio);
 809                 kfree(recover);
 810         }
 811 }
 812
 813 /*
 814  * scrub_handle_errored_block gets called when either verification of the
 815  * pages failed or the bio failed to read, e.g. with EIO. In the latter
 816  * case, this function handles all pages in the bio, even though only one
 817  * may be bad.
 818  * The goal of this function is to repair the errored block by using the
 819  * contents of one of the mirrors.
 820  */
 821 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
 822 {
 823         struct scrub_ctx *sctx = sblock_to_check->sctx;
 824         struct btrfs_device *dev;
 825         struct btrfs_fs_info *fs_info;
 826         u64 logical;
 827         unsigned int failed_mirror_index;
 828         unsigned int is_metadata;
 829         unsigned int have_csum;
 830         struct scrub_block *sblocks_for_recheck; /* holds one for each mirror */
 831         struct scrub_block *sblock_bad;
 832         int ret;
 833         int mirror_index;
 834         int page_num;
 835         int success;
 836         bool full_stripe_locked;
 837         unsigned int nofs_flag;
 838         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
 839                                       DEFAULT_RATELIMIT_BURST);
 840
 841         BUG_ON(sblock_to_check->page_count < 1);
 842         fs_info = sctx->fs_info;
 843         if (sblock_to_check->pagev[0]->flags & BTRFS_EXTENT_FLAG_SUPER) {
 844                 /*
 845                  * if we find an error in a super block, we just report it.
 846                  * They will get written with the next transaction commit
 847                  * anyway
 848                  */
 849                 spin_lock(&sctx->stat_lock);
 850                 ++sctx->stat.super_errors;
 851                 spin_unlock(&sctx->stat_lock);
 852                 return 0;
 853         }
 854         logical = sblock_to_check->pagev[0]->logical;
 855         BUG_ON(sblock_to_check->pagev[0]->mirror_num < 1);
 856         failed_mirror_index = sblock_to_check->pagev[0]->mirror_num - 1;
 857         is_metadata = !(sblock_to_check->pagev[0]->flags &
 858                         BTRFS_EXTENT_FLAG_DATA);
 859         have_csum = sblock_to_check->pagev[0]->have_csum;
 860         dev = sblock_to_check->pagev[0]->dev;
 861
 862         /*
 863          * We must use GFP_NOFS because the scrub task might be waiting for a
 864          * worker task executing this function and in turn a transaction commit
 865          * might be waiting the scrub task to pause (which needs to wait for all
 866          * the worker tasks to complete before pausing).
 867          * We do allocations in the workers through insert_full_stripe_lock()
 868          * and scrub_add_page_to_wr_bio(), which happens down the call chain of
 869          * this function.
 870          */
 871         nofs_flag = memalloc_nofs_save();
 872         /*
 873          * For RAID5/6, race can happen for a different device scrub thread.
 874          * For data corruption, Parity and Data threads will both try
 875          * to recovery the data.
 876          * Race can lead to doubly added csum error, or even unrecoverable
 877          * error.
 878          */
 879         ret = lock_full_stripe(fs_info, logical, &full_stripe_locked);
 880         if (ret < 0) {
 881                 memalloc_nofs_restore(nofs_flag);
 882                 spin_lock(&sctx->stat_lock);
 883                 if (ret == -ENOMEM)
 884                         sctx->stat.malloc_errors++;
 885                 sctx->stat.read_errors++;
 886                 sctx->stat.uncorrectable_errors++;
 887                 spin_unlock(&sctx->stat_lock);
 888                 return ret;
 889         }
 890
 891         /*
 892          * read all mirrors one after the other. This includes to
 893          * re-read the extent or metadata block that failed (that was
 894          * the cause that this fixup code is called) another time,
 895          * page by page this time in order to know which pages
 896          * caused I/O errors and which ones are good (for all mirrors).
 897          * It is the goal to handle the situation when more than one
 898          * mirror contains I/O errors, but the errors do not
 899          * overlap, i.e. the data can be repaired by selecting the
 900          * pages from those mirrors without I/O error on the
 901          * particular pages. One example (with blocks >= 2 * PAGE_SIZE)
 902          * would be that mirror #1 has an I/O error on the first page,
 903          * the second page is good, and mirror #2 has an I/O error on
 904          * the second page, but the first page is good.
 905          * Then the first page of the first mirror can be repaired by
 906          * taking the first page of the second mirror, and the
 907          * second page of the second mirror can be repaired by
 908          * copying the contents of the 2nd page of the 1st mirror.
 909          * One more note: if the pages of one mirror contain I/O
 910          * errors, the checksum cannot be verified. In order to get
 911          * the best data for repairing, the first attempt is to find
 912          * a mirror without I/O errors and with a validated checksum.
 913          * Only if this is not possible, the pages are picked from
 914          * mirrors with I/O errors without considering the checksum.
 915          * If the latter is the case, at the end, the checksum of the
 916          * repaired area is verified in order to correctly maintain
 917          * the statistics.
 918          */
 919
 920         sblocks_for_recheck = kcalloc(BTRFS_MAX_MIRRORS,
 921                                       sizeof(*sblocks_for_recheck), GFP_KERNEL);
 922         if (!sblocks_for_recheck) {
 923                 spin_lock(&sctx->stat_lock);
 924                 sctx->stat.malloc_errors++;
 925                 sctx->stat.read_errors++;
 926                 sctx->stat.uncorrectable_errors++;
 927                 spin_unlock(&sctx->stat_lock);
 928                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 929                 goto out;
 930         }
 931
 932         /* setup the context, map the logical blocks and alloc the pages */
 933         ret = scrub_setup_recheck_block(sblock_to_check, sblocks_for_recheck);
 934         if (ret) {
 935                 spin_lock(&sctx->stat_lock);
 936                 sctx->stat.read_errors++;
 937                 sctx->stat.uncorrectable_errors++;
 938                 spin_unlock(&sctx->stat_lock);
 939                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 940                 goto out;
 941         }
 942         BUG_ON(failed_mirror_index >= BTRFS_MAX_MIRRORS);
 943         sblock_bad = sblocks_for_recheck + failed_mirror_index;
 944
 945         /* build and submit the bios for the failed mirror, check checksums */
 946         scrub_recheck_block(fs_info, sblock_bad, 1);
 947
 948         if (!sblock_bad->header_error && !sblock_bad->checksum_error &&
 949             sblock_bad->no_io_error_seen) {
 950                 /*
 951                  * the error disappeared after reading page by page, or
 952                  * the area was part of a huge bio and other parts of the
 953                  * bio caused I/O errors, or the block layer merged several
 954                  * read requests into one and the error is caused by a
 955                  * different bio (usually one of the two latter cases is
 956                  * the cause)
 957                  */
 958                 spin_lock(&sctx->stat_lock);
 959                 sctx->stat.unverified_errors++;
 960                 sblock_to_check->data_corrected = 1;
 961                 spin_unlock(&sctx->stat_lock);
 962
 963                 if (sctx->is_dev_replace)
 964                         scrub_write_block_to_dev_replace(sblock_bad);
 965                 goto out;
 966         }
 967
 968         if (!sblock_bad->no_io_error_seen) {
 969                 spin_lock(&sctx->stat_lock);
 970                 sctx->stat.read_errors++;
 971                 spin_unlock(&sctx->stat_lock);
 972                 if (__ratelimit(&_rs))
 973                         scrub_print_warning("i/o error", sblock_to_check);
 974                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
 975         } else if (sblock_bad->checksum_error) {
 976                 spin_lock(&sctx->stat_lock);
 977                 sctx->stat.csum_errors++;
 978                 spin_unlock(&sctx->stat_lock);
 979                 if (__ratelimit(&_rs))
 980                         scrub_print_warning("checksum error", sblock_to_check);
 981                 btrfs_dev_stat_inc_and_print(dev,
 982                                              BTRFS_DEV_STAT_CORRUPTION_ERRS);
 983         } else if (sblock_bad->header_error) {
 984                 spin_lock(&sctx->stat_lock);
 985                 sctx->stat.verify_errors++;
 986                 spin_unlock(&sctx->stat_lock);
 987                 if (__ratelimit(&_rs))
 988                         scrub_print_warning("checksum/header error",
 989                                             sblock_to_check);
 990                 if (sblock_bad->generation_error)
 991                         btrfs_dev_stat_inc_and_print(dev,
 992                                 BTRFS_DEV_STAT_GENERATION_ERRS);
 993                 else
 994                         btrfs_dev_stat_inc_and_print(dev,
 995                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
 996         }
 997
 998         if (sctx->readonly) {
 999                 ASSERT(!sctx->is_dev_replace);
1000                 goto out;
1001         }
1002
1003         /*
1004          * now build and submit the bios for the other mirrors, check
1005          * checksums.
1006          * First try to pick the mirror which is completely without I/O
1007          * errors and also does not have a checksum error.
1008          * If one is found, and if a checksum is present, the full block
1009          * that is known to contain an error is rewritten. Afterwards
1010          * the block is known to be corrected.
1011          * If a mirror is found which is completely correct, and no
1012          * checksum is present, only those pages are rewritten that had
1013          * an I/O error in the block to be repaired, since it cannot be
1014          * determined, which copy of the other pages is better (and it
1015          * could happen otherwise that a correct page would be
1016          * overwritten by a bad one).
1017          */
1018         for (mirror_index = 0; ;mirror_index++) {
1019                 struct scrub_block *sblock_other;
1020
1021                 if (mirror_index == failed_mirror_index)
1022                         continue;
1023
1024                 /* raid56's mirror can be more than BTRFS_MAX_MIRRORS */
1025                 if (!scrub_is_page_on_raid56(sblock_bad->pagev[0])) {
1026                         if (mirror_index >= BTRFS_MAX_MIRRORS)
1027                                 break;
1028                         if (!sblocks_for_recheck[mirror_index].page_count)
1029                                 break;
1030
1031                         sblock_other = sblocks_for_recheck + mirror_index;
1032                 } else {
1033                         struct scrub_recover *r = sblock_bad->pagev[0]->recover;
1034                         int max_allowed = r->bbio->num_stripes -
1035                                                 r->bbio->num_tgtdevs;
1036
1037                         if (mirror_index >= max_allowed)
1038                                 break;
1039                         if (!sblocks_for_recheck[1].page_count)
1040                                 break;
1041
1042                         ASSERT(failed_mirror_index == 0);
1043                         sblock_other = sblocks_for_recheck + 1;
1044                         sblock_other->pagev[0]->mirror_num = 1 + mirror_index;
1045                 }
1046
1047                 /* build and submit the bios, check checksums */
1048                 scrub_recheck_block(fs_info, sblock_other, 0);
1049
1050                 if (!sblock_other->header_error &&
1051                     !sblock_other->checksum_error &&
1052                     sblock_other->no_io_error_seen) {
1053                         if (sctx->is_dev_replace) {
1054                                 scrub_write_block_to_dev_replace(sblock_other);
1055                                 goto corrected_error;
1056                         } else {
1057                                 ret = scrub_repair_block_from_good_copy(
1058                                                 sblock_bad, sblock_other);
1059                                 if (!ret)
1060                                         goto corrected_error;
1061                         }
1062                 }
1063         }
1064
1065         if (sblock_bad->no_io_error_seen && !sctx->is_dev_replace)
1066                 goto did_not_correct_error;
1067
1068         /*
1069          * In case of I/O errors in the area that is supposed to be
1070          * repaired, continue by picking good copies of those pages.
1071          * Select the good pages from mirrors to rewrite bad pages from
1072          * the area to fix. Afterwards verify the checksum of the block
1073          * that is supposed to be repaired. This verification step is
1074          * only done for the purpose of statistic counting and for the
1075          * final scrub report, whether errors remain.
1076          * A perfect algorithm could make use of the checksum and try
1077          * all possible combinations of pages from the different mirrors
1078          * until the checksum verification succeeds. For example, when
1079          * the 2nd page of mirror #1 faces I/O errors, and the 2nd page
1080          * of mirror #2 is readable but the final checksum test fails,
1081          * then the 2nd page of mirror #3 could be tried, whether now
1082          * the final checksum succeeds. But this would be a rare
1083          * exception and is therefore not implemented. At least it is
1084          * avoided that the good copy is overwritten.
1085          * A more useful improvement would be to pick the sectors
1086          * without I/O error based on sector sizes (512 bytes on legacy
1087          * disks) instead of on PAGE_SIZE. Then maybe 512 byte of one
1088          * mirror could be repaired by taking 512 byte of a different
1089          * mirror, even if other 512 byte sectors in the same PAGE_SIZE
1090          * area are unreadable.
1091          */
1092         success = 1;
1093         for (page_num = 0; page_num < sblock_bad->page_count;
1094              page_num++) {
1095                 struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1096                 struct scrub_block *sblock_other = NULL;
1097
1098                 /* skip no-io-error page in scrub */
1099                 if (!page_bad->io_error && !sctx->is_dev_replace)
1100                         continue;
1101
1102                 if (scrub_is_page_on_raid56(sblock_bad->pagev[0])) {
1103                         /*
1104                          * In case of dev replace, if raid56 rebuild process
1105                          * didn't work out correct data, then copy the content
1106                          * in sblock_bad to make sure target device is identical
1107                          * to source device, instead of writing garbage data in
1108                          * sblock_for_recheck array to target device.
1109                          */
1110                         sblock_other = NULL;
1111                 } else if (page_bad->io_error) {
1112                         /* try to find no-io-error page in mirrors */
1113                         for (mirror_index = 0;
1114                              mirror_index < BTRFS_MAX_MIRRORS &&
1115                              sblocks_for_recheck[mirror_index].page_count > 0;
1116                              mirror_index++) {
1117                                 if (!sblocks_for_recheck[mirror_index].
1118                                     pagev[page_num]->io_error) {
1119                                         sblock_other = sblocks_for_recheck +
1120                                                        mirror_index;
1121                                         break;
1122                                 }
1123                         }
1124                         if (!sblock_other)
1125                                 success = 0;
1126                 }
1127
1128                 if (sctx->is_dev_replace) {
1129                         /*
1130                          * did not find a mirror to fetch the page
1131                          * from. scrub_write_page_to_dev_replace()
1132                          * handles this case (page->io_error), by
1133                          * filling the block with zeros before
1134                          * submitting the write request
1135                          */
1136                         if (!sblock_other)
1137                                 sblock_other = sblock_bad;
1138
1139                         if (scrub_write_page_to_dev_replace(sblock_other,
1140                                                             page_num) != 0) {
1141                                 atomic64_inc(
1142                                         &fs_info->dev_replace.num_write_errors);
1143                                 success = 0;
1144                         }
1145                 } else if (sblock_other) {
1146                         ret = scrub_repair_page_from_good_copy(sblock_bad,
1147                                                                sblock_other,
1148                                                                page_num, 0);
1149                         if (0 == ret)
1150                                 page_bad->io_error = 0;
1151                         else
1152                                 success = 0;
1153                 }
1154         }
1155
1156         if (success && !sctx->is_dev_replace) {
1157                 if (is_metadata || have_csum) {
1158                         /*
1159                          * need to verify the checksum now that all
1160                          * sectors on disk are repaired (the write
1161                          * request for data to be repaired is on its way).
1162                          * Just be lazy and use scrub_recheck_block()
1163                          * which re-reads the data before the checksum
1164                          * is verified, but most likely the data comes out
1165                          * of the page cache.
1166                          */
1167                         scrub_recheck_block(fs_info, sblock_bad, 1);
1168                         if (!sblock_bad->header_error &&
1169                             !sblock_bad->checksum_error &&
1170                             sblock_bad->no_io_error_seen)
1171                                 goto corrected_error;
1172                         else
1173                                 goto did_not_correct_error;
1174                 } else {
1175 corrected_error:
1176                         spin_lock(&sctx->stat_lock);
1177                         sctx->stat.corrected_errors++;
1178                         sblock_to_check->data_corrected = 1;
1179                         spin_unlock(&sctx->stat_lock);
1180                         btrfs_err_rl_in_rcu(fs_info,
1181                                 "fixed up error at logical %llu on dev %s",
1182                                 logical, rcu_str_deref(dev->name));
1183                 }
1184         } else {
1185 did_not_correct_error:
1186                 spin_lock(&sctx->stat_lock);
1187                 sctx->stat.uncorrectable_errors++;
1188                 spin_unlock(&sctx->stat_lock);
1189                 btrfs_err_rl_in_rcu(fs_info,
1190                         "unable to fixup (regular) error at logical %llu on dev %s",
1191                         logical, rcu_str_deref(dev->name));
1192         }
1193
1194 out:
1195         if (sblocks_for_recheck) {
1196                 for (mirror_index = 0; mirror_index < BTRFS_MAX_MIRRORS;
1197                      mirror_index++) {
1198                         struct scrub_block *sblock = sblocks_for_recheck +
1199                                                      mirror_index;
1200                         struct scrub_recover *recover;
1201                         int page_index;
1202
1203                         for (page_index = 0; page_index < sblock->page_count;
1204                              page_index++) {
1205                                 sblock->pagev[page_index]->sblock = NULL;
1206                                 recover = sblock->pagev[page_index]->recover;
1207                                 if (recover) {
1208                                         scrub_put_recover(fs_info, recover);
1209                                         sblock->pagev[page_index]->recover =
1210                                                                         NULL;
1211                                 }
1212                                 scrub_page_put(sblock->pagev[page_index]);
1213                         }
1214                 }
1215                 kfree(sblocks_for_recheck);
1216         }
1217
1218         ret = unlock_full_stripe(fs_info, logical, full_stripe_locked);
1219         memalloc_nofs_restore(nofs_flag);
1220         if (ret < 0)
1221                 return ret;
1222         return 0;
1223 }
1224
1225 static inline int scrub_nr_raid_mirrors(struct btrfs_bio *bbio)
1226 {
1227         if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID5)
1228                 return 2;
1229         else if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID6)
1230                 return 3;
1231         else
1232                 return (int)bbio->num_stripes;
1233 }
1234
1235 static inline void scrub_stripe_index_and_offset(u64 logical, u64 map_type,
1236                                                  u64 *raid_map,
1237                                                  u64 mapped_length,
1238                                                  int nstripes, int mirror,
1239                                                  int *stripe_index,
1240                                                  u64 *stripe_offset)
1241 {
1242         int i;
1243
1244         if (map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
1245                 /* RAID5/6 */
1246                 for (i = 0; i < nstripes; i++) {
1247                         if (raid_map[i] == RAID6_Q_STRIPE ||
1248                             raid_map[i] == RAID5_P_STRIPE)
1249                                 continue;
1250
1251                         if (logical >= raid_map[i] &&
1252                             logical < raid_map[i] + mapped_length)
1253                                 break;
1254                 }
1255
1256                 *stripe_index = i;
1257                 *stripe_offset = logical - raid_map[i];
1258         } else {
1259                 /* The other RAID type */
1260                 *stripe_index = mirror;
1261                 *stripe_offset = 0;
1262         }
1263 }
1264
1265 static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
1266                                      struct scrub_block *sblocks_for_recheck)
1267 {
1268         struct scrub_ctx *sctx = original_sblock->sctx;
1269         struct btrfs_fs_info *fs_info = sctx->fs_info;
1270         u64 length = original_sblock->page_count * PAGE_SIZE;
1271         u64 logical = original_sblock->pagev[0]->logical;
1272         u64 generation = original_sblock->pagev[0]->generation;
1273         u64 flags = original_sblock->pagev[0]->flags;
1274         u64 have_csum = original_sblock->pagev[0]->have_csum;
1275         struct scrub_recover *recover;
1276         struct btrfs_bio *bbio;
1277         u64 sublen;
1278         u64 mapped_length;
1279         u64 stripe_offset;
1280         int stripe_index;
1281         int page_index = 0;
1282         int mirror_index;
1283         int nmirrors;
1284         int ret;
1285
1286         /*
1287          * note: the two members refs and outstanding_pages
1288          * are not used (and not set) in the blocks that are used for
1289          * the recheck procedure
1290          */
1291
1292         while (length > 0) {
1293                 sublen = min_t(u64, length, PAGE_SIZE);
1294                 mapped_length = sublen;
1295                 bbio = NULL;
1296
1297                 /*
1298                  * with a length of PAGE_SIZE, each returned stripe
1299                  * represents one mirror
1300                  */
1301                 btrfs_bio_counter_inc_blocked(fs_info);
1302                 ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS,
1303                                 logical, &mapped_length, &bbio);
1304                 if (ret || !bbio || mapped_length < sublen) {
1305                         btrfs_put_bbio(bbio);
1306                         btrfs_bio_counter_dec(fs_info);
1307                         return -EIO;
1308                 }
1309
1310                 recover = kzalloc(sizeof(struct scrub_recover), GFP_NOFS);
1311                 if (!recover) {
1312                         btrfs_put_bbio(bbio);
1313                         btrfs_bio_counter_dec(fs_info);
1314                         return -ENOMEM;
1315                 }
1316
1317                 refcount_set(&recover->refs, 1);
1318                 recover->bbio = bbio;
1319                 recover->map_length = mapped_length;
1320
1321                 BUG_ON(page_index >= SCRUB_MAX_PAGES_PER_BLOCK);
1322
1323                 nmirrors = min(scrub_nr_raid_mirrors(bbio), BTRFS_MAX_MIRRORS);
1324
1325                 for (mirror_index = 0; mirror_index < nmirrors;
1326                      mirror_index++) {
1327                         struct scrub_block *sblock;
1328                         struct scrub_page *page;
1329
1330                         sblock = sblocks_for_recheck + mirror_index;
1331                         sblock->sctx = sctx;
1332
1333                         page = kzalloc(sizeof(*page), GFP_NOFS);
1334                         if (!page) {
1335 leave_nomem:
1336                                 spin_lock(&sctx->stat_lock);
1337                                 sctx->stat.malloc_errors++;
1338                                 spin_unlock(&sctx->stat_lock);
1339                                 scrub_put_recover(fs_info, recover);
1340                                 return -ENOMEM;
1341                         }
1342                         scrub_page_get(page);
1343                         sblock->pagev[page_index] = page;
1344                         page->sblock = sblock;
1345                         page->flags = flags;
1346                         page->generation = generation;
1347                         page->logical = logical;
1348                         page->have_csum = have_csum;
1349                         if (have_csum)
1350                                 memcpy(page->csum,
1351                                        original_sblock->pagev[0]->csum,
1352                                        sctx->csum_size);
1353
1354                         scrub_stripe_index_and_offset(logical,
1355                                                       bbio->map_type,
1356                                                       bbio->raid_map,
1357                                                       mapped_length,
1358                                                       bbio->num_stripes -
1359                                                       bbio->num_tgtdevs,
1360                                                       mirror_index,
1361                                                       &stripe_index,
1362                                                       &stripe_offset);
1363                         page->physical = bbio->stripes[stripe_index].physical +
1364                                          stripe_offset;
1365                         page->dev = bbio->stripes[stripe_index].dev;
1366
1367                         BUG_ON(page_index >= original_sblock->page_count);
1368                         page->physical_for_dev_replace =
1369                                 original_sblock->pagev[page_index]->
1370                                 physical_for_dev_replace;
1371                         /* for missing devices, dev->bdev is NULL */
1372                         page->mirror_num = mirror_index + 1;
1373                         sblock->page_count++;
1374                         page->page = alloc_page(GFP_NOFS);
1375                         if (!page->page)
1376                                 goto leave_nomem;
1377
1378                         scrub_get_recover(recover);
1379                         page->recover = recover;
1380                 }
1381                 scrub_put_recover(fs_info, recover);
1382                 length -= sublen;
1383                 logical += sublen;
1384                 page_index++;
1385         }
1386
1387         return 0;
1388 }
1389
1390 static void scrub_bio_wait_endio(struct bio *bio)
1391 {
1392         complete(bio->bi_private);
1393 }
1394
1395 static int scrub_submit_raid56_bio_wait(struct btrfs_fs_info *fs_info,
1396                                         struct bio *bio,
1397                                         struct scrub_page *page)
1398 {
1399         DECLARE_COMPLETION_ONSTACK(done);
1400         int ret;
1401         int mirror_num;
1402
1403         bio->bi_iter.bi_sector = page->logical >> 9;
1404         bio->bi_private = &done;
1405         bio->bi_end_io = scrub_bio_wait_endio;
1406
1407         mirror_num = page->sblock->pagev[0]->mirror_num;
1408         ret = raid56_parity_recover(fs_info, bio, page->recover->bbio,
1409                                     page->recover->map_length,
1410                                     mirror_num, 0);
1411         if (ret)
1412                 return ret;
1413
1414         wait_for_completion_io(&done);
1415         return blk_status_to_errno(bio->bi_status);
1416 }
1417
1418 static void scrub_recheck_block_on_raid56(struct btrfs_fs_info *fs_info,
1419                                           struct scrub_block *sblock)
1420 {
1421         struct scrub_page *first_page = sblock->pagev[0];
1422         struct bio *bio;
1423         int page_num;
1424
1425         /* All pages in sblock belong to the same stripe on the same device. */
1426         ASSERT(first_page->dev);
1427         if (!first_page->dev->bdev)
1428                 goto out;
1429
1430         bio = btrfs_io_bio_alloc(BIO_MAX_PAGES);
1431         bio_set_dev(bio, first_page->dev->bdev);
1432
1433         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1434                 struct scrub_page *page = sblock->pagev[page_num];
1435
1436                 WARN_ON(!page->page);
1437                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1438         }
1439
1440         if (scrub_submit_raid56_bio_wait(fs_info, bio, first_page)) {
1441                 bio_put(bio);
1442                 goto out;
1443         }
1444
1445         bio_put(bio);
1446
1447         scrub_recheck_block_checksum(sblock);
1448
1449         return;
1450 out:
1451         for (page_num = 0; page_num < sblock->page_count; page_num++)
1452                 sblock->pagev[page_num]->io_error = 1;
1453
1454         sblock->no_io_error_seen = 0;
1455 }
1456
1457 /*
1458  * this function will check the on disk data for checksum errors, header
1459  * errors and read I/O errors. If any I/O errors happen, the exact pages
1460  * which are errored are marked as being bad. The goal is to enable scrub
1461  * to take those pages that are not errored from all the mirrors so that
1462  * the pages that are errored in the just handled mirror can be repaired.
1463  */
1464 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
1465                                 struct scrub_block *sblock,
1466                                 int retry_failed_mirror)
1467 {
1468         int page_num;
1469
1470         sblock->no_io_error_seen = 1;
1471
1472         /* short cut for raid56 */
1473         if (!retry_failed_mirror && scrub_is_page_on_raid56(sblock->pagev[0]))
1474                 return scrub_recheck_block_on_raid56(fs_info, sblock);
1475
1476         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1477                 struct bio *bio;
1478                 struct scrub_page *page = sblock->pagev[page_num];
1479
1480                 if (page->dev->bdev == NULL) {
1481                         page->io_error = 1;
1482                         sblock->no_io_error_seen = 0;
1483                         continue;
1484                 }
1485
1486                 WARN_ON(!page->page);
1487                 bio = btrfs_io_bio_alloc(1);
1488                 bio_set_dev(bio, page->dev->bdev);
1489
1490                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1491                 bio->bi_iter.bi_sector = page->physical >> 9;
1492                 bio->bi_opf = REQ_OP_READ;
1493
1494                 if (btrfsic_submit_bio_wait(bio)) {
1495                         page->io_error = 1;
1496                         sblock->no_io_error_seen = 0;
1497                 }
1498
1499                 bio_put(bio);
1500         }
1501
1502         if (sblock->no_io_error_seen)
1503                 scrub_recheck_block_checksum(sblock);
1504 }
1505
1506 static inline int scrub_check_fsid(u8 fsid[],
1507                                    struct scrub_page *spage)
1508 {
1509         struct btrfs_fs_devices *fs_devices = spage->dev->fs_devices;
1510         int ret;
1511
1512         ret = memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
1513         return !ret;
1514 }
1515
1516 static void scrub_recheck_block_checksum(struct scrub_block *sblock)
1517 {
1518         sblock->header_error = 0;
1519         sblock->checksum_error = 0;
1520         sblock->generation_error = 0;
1521
1522         if (sblock->pagev[0]->flags & BTRFS_EXTENT_FLAG_DATA)
1523                 scrub_checksum_data(sblock);
1524         else
1525                 scrub_checksum_tree_block(sblock);
1526 }
1527
1528 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
1529                                              struct scrub_block *sblock_good)
1530 {
1531         int page_num;
1532         int ret = 0;
1533
1534         for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
1535                 int ret_sub;
1536
1537                 ret_sub = scrub_repair_page_from_good_copy(sblock_bad,
1538                                                            sblock_good,
1539                                                            page_num, 1);
1540                 if (ret_sub)
1541                         ret = ret_sub;
1542         }
1543
1544         return ret;
1545 }
1546
1547 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
1548                                             struct scrub_block *sblock_good,
1549                                             int page_num, int force_write)
1550 {
1551         struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1552         struct scrub_page *page_good = sblock_good->pagev[page_num];
1553         struct btrfs_fs_info *fs_info = sblock_bad->sctx->fs_info;
1554
1555         BUG_ON(page_bad->page == NULL);
1556         BUG_ON(page_good->page == NULL);
1557         if (force_write || sblock_bad->header_error ||
1558             sblock_bad->checksum_error || page_bad->io_error) {
1559                 struct bio *bio;
1560                 int ret;
1561
1562                 if (!page_bad->dev->bdev) {
1563                         btrfs_warn_rl(fs_info,
1564                                 "scrub_repair_page_from_good_copy(bdev == NULL) is unexpected");
1565                         return -EIO;
1566                 }
1567
1568                 bio = btrfs_io_bio_alloc(1);
1569                 bio_set_dev(bio, page_bad->dev->bdev);
1570                 bio->bi_iter.bi_sector = page_bad->physical >> 9;
1571                 bio->bi_opf = REQ_OP_WRITE;
1572
1573                 ret = bio_add_page(bio, page_good->page, PAGE_SIZE, 0);
1574                 if (PAGE_SIZE != ret) {
1575                         bio_put(bio);
1576                         return -EIO;
1577                 }
1578
1579                 if (btrfsic_submit_bio_wait(bio)) {
1580                         btrfs_dev_stat_inc_and_print(page_bad->dev,
1581                                 BTRFS_DEV_STAT_WRITE_ERRS);
1582                         atomic64_inc(&fs_info->dev_replace.num_write_errors);
1583                         bio_put(bio);
1584                         return -EIO;
1585                 }
1586                 bio_put(bio);
1587         }
1588
1589         return 0;
1590 }
1591
1592 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock)
1593 {
1594         struct btrfs_fs_info *fs_info = sblock->sctx->fs_info;
1595         int page_num;
1596
1597         /*
1598          * This block is used for the check of the parity on the source device,
1599          * so the data needn't be written into the destination device.
1600          */
1601         if (sblock->sparity)
1602                 return;
1603
1604         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1605                 int ret;
1606
1607                 ret = scrub_write_page_to_dev_replace(sblock, page_num);
1608                 if (ret)
1609                         atomic64_inc(&fs_info->dev_replace.num_write_errors);
1610         }
1611 }
1612
1613 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
1614                                            int page_num)
1615 {
1616         struct scrub_page *spage = sblock->pagev[page_num];
1617
1618         BUG_ON(spage->page == NULL);
1619         if (spage->io_error) {
1620                 void *mapped_buffer = kmap_atomic(spage->page);
1621
1622                 clear_page(mapped_buffer);
1623                 flush_dcache_page(spage->page);
1624                 kunmap_atomic(mapped_buffer);
1625         }
1626         return scrub_add_page_to_wr_bio(sblock->sctx, spage);
1627 }
1628
1629 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
1630                                     struct scrub_page *spage)
1631 {
1632         struct scrub_bio *sbio;
1633         int ret;
1634
1635         mutex_lock(&sctx->wr_lock);
1636 again:
1637         if (!sctx->wr_curr_bio) {
1638                 sctx->wr_curr_bio = kzalloc(sizeof(*sctx->wr_curr_bio),
1639                                               GFP_KERNEL);
1640                 if (!sctx->wr_curr_bio) {
1641                         mutex_unlock(&sctx->wr_lock);
1642                         return -ENOMEM;
1643                 }
1644                 sctx->wr_curr_bio->sctx = sctx;
1645                 sctx->wr_curr_bio->page_count = 0;
1646         }
1647         sbio = sctx->wr_curr_bio;
1648         if (sbio->page_count == 0) {
1649                 struct bio *bio;
1650
1651                 sbio->physical = spage->physical_for_dev_replace;
1652                 sbio->logical = spage->logical;
1653                 sbio->dev = sctx->wr_tgtdev;
1654                 bio = sbio->bio;
1655                 if (!bio) {
1656                         bio = btrfs_io_bio_alloc(sctx->pages_per_wr_bio);
1657                         sbio->bio = bio;
1658                 }
1659
1660                 bio->bi_private = sbio;
1661                 bio->bi_end_io = scrub_wr_bio_end_io;
1662                 bio_set_dev(bio, sbio->dev->bdev);
1663                 bio->bi_iter.bi_sector = sbio->physical >> 9;
1664                 bio->bi_opf = REQ_OP_WRITE;
1665                 sbio->status = 0;
1666         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
1667                    spage->physical_for_dev_replace ||
1668                    sbio->logical + sbio->page_count * PAGE_SIZE !=
1669                    spage->logical) {
1670                 scrub_wr_submit(sctx);
1671                 goto again;
1672         }
1673
1674         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
1675         if (ret != PAGE_SIZE) {
1676                 if (sbio->page_count < 1) {
1677                         bio_put(sbio->bio);
1678                         sbio->bio = NULL;
1679                         mutex_unlock(&sctx->wr_lock);
1680                         return -EIO;
1681                 }
1682                 scrub_wr_submit(sctx);
1683                 goto again;
1684         }
1685
1686         sbio->pagev[sbio->page_count] = spage;
1687         scrub_page_get(spage);
1688         sbio->page_count++;
1689         if (sbio->page_count == sctx->pages_per_wr_bio)
1690                 scrub_wr_submit(sctx);
1691         mutex_unlock(&sctx->wr_lock);
1692
1693         return 0;
1694 }
1695
1696 static void scrub_wr_submit(struct scrub_ctx *sctx)
1697 {
1698         struct scrub_bio *sbio;
1699
1700         if (!sctx->wr_curr_bio)
1701                 return;
1702
1703         sbio = sctx->wr_curr_bio;
1704         sctx->wr_curr_bio = NULL;
1705         WARN_ON(!sbio->bio->bi_disk);
1706         scrub_pending_bio_inc(sctx);
1707         /* process all writes in a single worker thread. Then the block layer
1708          * orders the requests before sending them to the driver which
1709          * doubled the write performance on spinning disks when measured
1710          * with Linux 3.5 */
1711         btrfsic_submit_bio(sbio->bio);
1712 }
1713
1714 static void scrub_wr_bio_end_io(struct bio *bio)
1715 {
1716         struct scrub_bio *sbio = bio->bi_private;
1717         struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
1718
1719         sbio->status = bio->bi_status;
1720         sbio->bio = bio;
1721
1722         btrfs_init_work(&sbio->work, scrub_wr_bio_end_io_worker, NULL, NULL);
1723         btrfs_queue_work(fs_info->scrub_wr_completion_workers, &sbio->work);
1724 }
1725
1726 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work)
1727 {
1728         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
1729         struct scrub_ctx *sctx = sbio->sctx;
1730         int i;
1731
1732         WARN_ON(sbio->page_count > SCRUB_PAGES_PER_WR_BIO);
1733         if (sbio->status) {
1734                 struct btrfs_dev_replace *dev_replace =
1735                         &sbio->sctx->fs_info->dev_replace;
1736
1737                 for (i = 0; i < sbio->page_count; i++) {
1738                         struct scrub_page *spage = sbio->pagev[i];
1739
1740                         spage->io_error = 1;
1741                         atomic64_inc(&dev_replace->num_write_errors);
1742                 }
1743         }
1744
1745         for (i = 0; i < sbio->page_count; i++)
1746                 scrub_page_put(sbio->pagev[i]);
1747
1748         bio_put(sbio->bio);
1749         kfree(sbio);
1750         scrub_pending_bio_dec(sctx);
1751 }
1752
1753 static int scrub_checksum(struct scrub_block *sblock)
1754 {
1755         u64 flags;
1756         int ret;
1757
1758         /*
1759          * No need to initialize these stats currently,
1760          * because this function only use return value
1761          * instead of these stats value.
1762          *
1763          * Todo:
1764          * always use stats
1765          */
1766         sblock->header_error = 0;
1767         sblock->generation_error = 0;
1768         sblock->checksum_error = 0;
1769
1770         WARN_ON(sblock->page_count < 1);
1771         flags = sblock->pagev[0]->flags;
1772         ret = 0;
1773         if (flags & BTRFS_EXTENT_FLAG_DATA)
1774                 ret = scrub_checksum_data(sblock);
1775         else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1776                 ret = scrub_checksum_tree_block(sblock);
1777         else if (flags & BTRFS_EXTENT_FLAG_SUPER)
1778                 (void)scrub_checksum_super(sblock);
1779         else
1780                 WARN_ON(1);
1781         if (ret)
1782                 scrub_handle_errored_block(sblock);
1783
1784         return ret;
1785 }
1786
1787 static int scrub_checksum_data(struct scrub_block *sblock)
1788 {
1789         struct scrub_ctx *sctx = sblock->sctx;
1790         struct btrfs_fs_info *fs_info = sctx->fs_info;
1791         SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
1792         u8 csum[BTRFS_CSUM_SIZE];
1793         u8 *on_disk_csum;
1794         struct page *page;
1795         void *buffer;
1796         u64 len;
1797         int index;
1798
1799         BUG_ON(sblock->page_count < 1);
1800         if (!sblock->pagev[0]->have_csum)
1801                 return 0;
1802
1803         shash->tfm = fs_info->csum_shash;
1804         crypto_shash_init(shash);
1805
1806         on_disk_csum = sblock->pagev[0]->csum;
1807         page = sblock->pagev[0]->page;
1808         buffer = kmap_atomic(page);
1809
1810         len = sctx->fs_info->sectorsize;
1811         index = 0;
1812         for (;;) {
1813                 u64 l = min_t(u64, len, PAGE_SIZE);
1814
1815                 crypto_shash_update(shash, buffer, l);
1816                 kunmap_atomic(buffer);
1817                 len -= l;
1818                 if (len == 0)
1819                         break;
1820                 index++;
1821                 BUG_ON(index >= sblock->page_count);
1822                 BUG_ON(!sblock->pagev[index]->page);
1823                 page = sblock->pagev[index]->page;
1824                 buffer = kmap_atomic(page);
1825         }
1826
1827         crypto_shash_final(shash, csum);
1828         if (memcmp(csum, on_disk_csum, sctx->csum_size))
1829                 sblock->checksum_error = 1;
1830
1831         return sblock->checksum_error;
1832 }
1833
1834 static int scrub_checksum_tree_block(struct scrub_block *sblock)
1835 {
1836         struct scrub_ctx *sctx = sblock->sctx;
1837         struct btrfs_header *h;
1838         struct btrfs_fs_info *fs_info = sctx->fs_info;
1839         SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
1840         u8 calculated_csum[BTRFS_CSUM_SIZE];
1841         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1842         struct page *page;
1843         void *mapped_buffer;
1844         u64 mapped_size;
1845         void *p;
1846         u64 len;
1847         int index;
1848
1849         shash->tfm = fs_info->csum_shash;
1850         crypto_shash_init(shash);
1851
1852         BUG_ON(sblock->page_count < 1);
1853         page = sblock->pagev[0]->page;
1854         mapped_buffer = kmap_atomic(page);
1855         h = (struct btrfs_header *)mapped_buffer;
1856         memcpy(on_disk_csum, h->csum, sctx->csum_size);
1857
1858         /*
1859          * we don't use the getter functions here, as we
1860          * a) don't have an extent buffer and
1861          * b) the page is already kmapped
1862          */
1863         if (sblock->pagev[0]->logical != btrfs_stack_header_bytenr(h))
1864                 sblock->header_error = 1;
1865
1866         if (sblock->pagev[0]->generation != btrfs_stack_header_generation(h)) {
1867                 sblock->header_error = 1;
1868                 sblock->generation_error = 1;
1869         }
1870
1871         if (!scrub_check_fsid(h->fsid, sblock->pagev[0]))
1872                 sblock->header_error = 1;
1873
1874         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
1875                    BTRFS_UUID_SIZE))
1876                 sblock->header_error = 1;
1877
1878         len = sctx->fs_info->nodesize - BTRFS_CSUM_SIZE;
1879         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1880         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1881         index = 0;
1882         for (;;) {
1883                 u64 l = min_t(u64, len, mapped_size);
1884
1885                 crypto_shash_update(shash, p, l);
1886                 kunmap_atomic(mapped_buffer);
1887                 len -= l;
1888                 if (len == 0)
1889                         break;
1890                 index++;
1891                 BUG_ON(index >= sblock->page_count);
1892                 BUG_ON(!sblock->pagev[index]->page);
1893                 page = sblock->pagev[index]->page;
1894                 mapped_buffer = kmap_atomic(page);
1895                 mapped_size = PAGE_SIZE;
1896                 p = mapped_buffer;
1897         }
1898
1899         crypto_shash_final(shash, calculated_csum);
1900         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1901                 sblock->checksum_error = 1;
1902
1903         return sblock->header_error || sblock->checksum_error;
1904 }
1905
1906 static int scrub_checksum_super(struct scrub_block *sblock)
1907 {
1908         struct btrfs_super_block *s;
1909         struct scrub_ctx *sctx = sblock->sctx;
1910         struct btrfs_fs_info *fs_info = sctx->fs_info;
1911         SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
1912         u8 calculated_csum[BTRFS_CSUM_SIZE];
1913         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1914         struct page *page;
1915         void *mapped_buffer;
1916         u64 mapped_size;
1917         void *p;
1918         int fail_gen = 0;
1919         int fail_cor = 0;
1920         u64 len;
1921         int index;
1922
1923         shash->tfm = fs_info->csum_shash;
1924         crypto_shash_init(shash);
1925
1926         BUG_ON(sblock->page_count < 1);
1927         page = sblock->pagev[0]->page;
1928         mapped_buffer = kmap_atomic(page);
1929         s = (struct btrfs_super_block *)mapped_buffer;
1930         memcpy(on_disk_csum, s->csum, sctx->csum_size);
1931
1932         if (sblock->pagev[0]->logical != btrfs_super_bytenr(s))
1933                 ++fail_cor;
1934
1935         if (sblock->pagev[0]->generation != btrfs_super_generation(s))
1936                 ++fail_gen;
1937
1938         if (!scrub_check_fsid(s->fsid, sblock->pagev[0]))
1939                 ++fail_cor;
1940
1941         len = BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE;
1942         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1943         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1944         index = 0;
1945         for (;;) {
1946                 u64 l = min_t(u64, len, mapped_size);
1947
1948                 crypto_shash_update(shash, p, l);
1949                 kunmap_atomic(mapped_buffer);
1950                 len -= l;
1951                 if (len == 0)
1952                         break;
1953                 index++;
1954                 BUG_ON(index >= sblock->page_count);
1955                 BUG_ON(!sblock->pagev[index]->page);
1956                 page = sblock->pagev[index]->page;
1957                 mapped_buffer = kmap_atomic(page);
1958                 mapped_size = PAGE_SIZE;
1959                 p = mapped_buffer;
1960         }
1961
1962         crypto_shash_final(shash, calculated_csum);
1963         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1964                 ++fail_cor;
1965
1966         if (fail_cor + fail_gen) {
1967                 /*
1968                  * if we find an error in a super block, we just report it.
1969                  * They will get written with the next transaction commit
1970                  * anyway
1971                  */
1972                 spin_lock(&sctx->stat_lock);
1973                 ++sctx->stat.super_errors;
1974                 spin_unlock(&sctx->stat_lock);
1975                 if (fail_cor)
1976                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1977                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
1978                 else
1979                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1980                                 BTRFS_DEV_STAT_GENERATION_ERRS);
1981         }
1982
1983         return fail_cor + fail_gen;
1984 }
1985
1986 static void scrub_block_get(struct scrub_block *sblock)
1987 {
1988         refcount_inc(&sblock->refs);
1989 }
1990
1991 static void scrub_block_put(struct scrub_block *sblock)
1992 {
1993         if (refcount_dec_and_test(&sblock->refs)) {
1994                 int i;
1995
1996                 if (sblock->sparity)
1997                         scrub_parity_put(sblock->sparity);
1998
1999                 for (i = 0; i < sblock->page_count; i++)
2000                         scrub_page_put(sblock->pagev[i]);
2001                 kfree(sblock);
2002         }
2003 }
2004
2005 static void scrub_page_get(struct scrub_page *spage)
2006 {
2007         atomic_inc(&spage->refs);
2008 }
2009
2010 static void scrub_page_put(struct scrub_page *spage)
2011 {
2012         if (atomic_dec_and_test(&spage->refs)) {
2013                 if (spage->page)
2014                         __free_page(spage->page);
2015                 kfree(spage);
2016         }
2017 }
2018
2019 static void scrub_submit(struct scrub_ctx *sctx)
2020 {
2021         struct scrub_bio *sbio;
2022
2023         if (sctx->curr == -1)
2024                 return;
2025
2026         sbio = sctx->bios[sctx->curr];
2027         sctx->curr = -1;
2028         scrub_pending_bio_inc(sctx);
2029         btrfsic_submit_bio(sbio->bio);
2030 }
2031
2032 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
2033                                     struct scrub_page *spage)
2034 {
2035         struct scrub_block *sblock = spage->sblock;
2036         struct scrub_bio *sbio;
2037         int ret;
2038
2039 again:
2040         /*
2041          * grab a fresh bio or wait for one to become available
2042          */
2043         while (sctx->curr == -1) {
2044                 spin_lock(&sctx->list_lock);
2045                 sctx->curr = sctx->first_free;
2046                 if (sctx->curr != -1) {
2047                         sctx->first_free = sctx->bios[sctx->curr]->next_free;
2048                         sctx->bios[sctx->curr]->next_free = -1;
2049                         sctx->bios[sctx->curr]->page_count = 0;
2050                         spin_unlock(&sctx->list_lock);
2051                 } else {
2052                         spin_unlock(&sctx->list_lock);
2053                         wait_event(sctx->list_wait, sctx->first_free != -1);
2054                 }
2055         }
2056         sbio = sctx->bios[sctx->curr];
2057         if (sbio->page_count == 0) {
2058                 struct bio *bio;
2059
2060                 sbio->physical = spage->physical;
2061                 sbio->logical = spage->logical;
2062                 sbio->dev = spage->dev;
2063                 bio = sbio->bio;
2064                 if (!bio) {
2065                         bio = btrfs_io_bio_alloc(sctx->pages_per_rd_bio);
2066                         sbio->bio = bio;
2067                 }
2068
2069                 bio->bi_private = sbio;
2070                 bio->bi_end_io = scrub_bio_end_io;
2071                 bio_set_dev(bio, sbio->dev->bdev);
2072                 bio->bi_iter.bi_sector = sbio->physical >> 9;
2073                 bio->bi_opf = REQ_OP_READ;
2074                 sbio->status = 0;
2075         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
2076                    spage->physical ||
2077                    sbio->logical + sbio->page_count * PAGE_SIZE !=
2078                    spage->logical ||
2079                    sbio->dev != spage->dev) {
2080                 scrub_submit(sctx);
2081                 goto again;
2082         }
2083
2084         sbio->pagev[sbio->page_count] = spage;
2085         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
2086         if (ret != PAGE_SIZE) {
2087                 if (sbio->page_count < 1) {
2088                         bio_put(sbio->bio);
2089                         sbio->bio = NULL;
2090                         return -EIO;
2091                 }
2092                 scrub_submit(sctx);
2093                 goto again;
2094         }
2095
2096         scrub_block_get(sblock); /* one for the page added to the bio */
2097         atomic_inc(&sblock->outstanding_pages);
2098         sbio->page_count++;
2099         if (sbio->page_count == sctx->pages_per_rd_bio)
2100                 scrub_submit(sctx);
2101
2102         return 0;
2103 }
2104
2105 static void scrub_missing_raid56_end_io(struct bio *bio)
2106 {
2107         struct scrub_block *sblock = bio->bi_private;
2108         struct btrfs_fs_info *fs_info = sblock->sctx->fs_info;
2109
2110         if (bio->bi_status)
2111                 sblock->no_io_error_seen = 0;
2112
2113         bio_put(bio);
2114
2115         btrfs_queue_work(fs_info->scrub_workers, &sblock->work);
2116 }
2117
2118 static void scrub_missing_raid56_worker(struct btrfs_work *work)
2119 {
2120         struct scrub_block *sblock = container_of(work, struct scrub_block, work);
2121         struct scrub_ctx *sctx = sblock->sctx;
2122         struct btrfs_fs_info *fs_info = sctx->fs_info;
2123         u64 logical;
2124         struct btrfs_device *dev;
2125
2126         logical = sblock->pagev[0]->logical;
2127         dev = sblock->pagev[0]->dev;
2128
2129         if (sblock->no_io_error_seen)
2130                 scrub_recheck_block_checksum(sblock);
2131
2132         if (!sblock->no_io_error_seen) {
2133                 spin_lock(&sctx->stat_lock);
2134                 sctx->stat.read_errors++;
2135                 spin_unlock(&sctx->stat_lock);
2136                 btrfs_err_rl_in_rcu(fs_info,
2137                         "IO error rebuilding logical %llu for dev %s",
2138                         logical, rcu_str_deref(dev->name));
2139         } else if (sblock->header_error || sblock->checksum_error) {
2140                 spin_lock(&sctx->stat_lock);
2141                 sctx->stat.uncorrectable_errors++;
2142                 spin_unlock(&sctx->stat_lock);
2143                 btrfs_err_rl_in_rcu(fs_info,
2144                         "failed to rebuild valid logical %llu for dev %s",
2145                         logical, rcu_str_deref(dev->name));
2146         } else {
2147                 scrub_write_block_to_dev_replace(sblock);
2148         }
2149
2150         if (sctx->is_dev_replace && sctx->flush_all_writes) {
2151                 mutex_lock(&sctx->wr_lock);
2152                 scrub_wr_submit(sctx);
2153                 mutex_unlock(&sctx->wr_lock);
2154         }
2155
2156         scrub_block_put(sblock);
2157         scrub_pending_bio_dec(sctx);
2158 }
2159
2160 static void scrub_missing_raid56_pages(struct scrub_block *sblock)
2161 {
2162         struct scrub_ctx *sctx = sblock->sctx;
2163         struct btrfs_fs_info *fs_info = sctx->fs_info;
2164         u64 length = sblock->page_count * PAGE_SIZE;
2165         u64 logical = sblock->pagev[0]->logical;
2166         struct btrfs_bio *bbio = NULL;
2167         struct bio *bio;
2168         struct btrfs_raid_bio *rbio;
2169         int ret;
2170         int i;
2171
2172         btrfs_bio_counter_inc_blocked(fs_info);
2173         ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,
2174                         &length, &bbio);
2175         if (ret || !bbio || !bbio->raid_map)
2176                 goto bbio_out;
2177
2178         if (WARN_ON(!sctx->is_dev_replace ||
2179                     !(bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK))) {
2180                 /*
2181                  * We shouldn't be scrubbing a missing device. Even for dev
2182                  * replace, we should only get here for RAID 5/6. We either
2183                  * managed to mount something with no mirrors remaining or
2184                  * there's a bug in scrub_remap_extent()/btrfs_map_block().
2185                  */
2186                 goto bbio_out;
2187         }
2188
2189         bio = btrfs_io_bio_alloc(0);
2190         bio->bi_iter.bi_sector = logical >> 9;
2191         bio->bi_private = sblock;
2192         bio->bi_end_io = scrub_missing_raid56_end_io;
2193
2194         rbio = raid56_alloc_missing_rbio(fs_info, bio, bbio, length);
2195         if (!rbio)
2196                 goto rbio_out;
2197
2198         for (i = 0; i < sblock->page_count; i++) {
2199                 struct scrub_page *spage = sblock->pagev[i];
2200
2201                 raid56_add_scrub_pages(rbio, spage->page, spage->logical);
2202         }
2203
2204         btrfs_init_work(&sblock->work, scrub_missing_raid56_worker, NULL, NULL);
2205         scrub_block_get(sblock);
2206         scrub_pending_bio_inc(sctx);
2207         raid56_submit_missing_rbio(rbio);
2208         return;
2209
2210 rbio_out:
2211         bio_put(bio);
2212 bbio_out:
2213         btrfs_bio_counter_dec(fs_info);
2214         btrfs_put_bbio(bbio);
2215         spin_lock(&sctx->stat_lock);
2216         sctx->stat.malloc_errors++;
2217         spin_unlock(&sctx->stat_lock);
2218 }
2219
2220 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
2221                        u64 physical, struct btrfs_device *dev, u64 flags,
2222                        u64 gen, int mirror_num, u8 *csum, int force,
2223                        u64 physical_for_dev_replace)
2224 {
2225         struct scrub_block *sblock;
2226         int index;
2227
2228         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2229         if (!sblock) {
2230                 spin_lock(&sctx->stat_lock);
2231                 sctx->stat.malloc_errors++;
2232                 spin_unlock(&sctx->stat_lock);
2233                 return -ENOMEM;
2234         }
2235
2236         /* one ref inside this function, plus one for each page added to
2237          * a bio later on */
2238         refcount_set(&sblock->refs, 1);
2239         sblock->sctx = sctx;
2240         sblock->no_io_error_seen = 1;
2241
2242         for (index = 0; len > 0; index++) {
2243                 struct scrub_page *spage;
2244                 u64 l = min_t(u64, len, PAGE_SIZE);
2245
2246                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2247                 if (!spage) {
2248 leave_nomem:
2249                         spin_lock(&sctx->stat_lock);
2250                         sctx->stat.malloc_errors++;
2251                         spin_unlock(&sctx->stat_lock);
2252                         scrub_block_put(sblock);
2253                         return -ENOMEM;
2254                 }
2255                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2256                 scrub_page_get(spage);
2257                 sblock->pagev[index] = spage;
2258                 spage->sblock = sblock;
2259                 spage->dev = dev;
2260                 spage->flags = flags;
2261                 spage->generation = gen;
2262                 spage->logical = logical;
2263                 spage->physical = physical;
2264                 spage->physical_for_dev_replace = physical_for_dev_replace;
2265                 spage->mirror_num = mirror_num;
2266                 if (csum) {
2267                         spage->have_csum = 1;
2268                         memcpy(spage->csum, csum, sctx->csum_size);
2269                 } else {
2270                         spage->have_csum = 0;
2271                 }
2272                 sblock->page_count++;
2273                 spage->page = alloc_page(GFP_KERNEL);
2274                 if (!spage->page)
2275                         goto leave_nomem;
2276                 len -= l;
2277                 logical += l;
2278                 physical += l;
2279                 physical_for_dev_replace += l;
2280         }
2281
2282         WARN_ON(sblock->page_count == 0);
2283         if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) {
2284                 /*
2285                  * This case should only be hit for RAID 5/6 device replace. See
2286                  * the comment in scrub_missing_raid56_pages() for details.
2287                  */
2288                 scrub_missing_raid56_pages(sblock);
2289         } else {
2290                 for (index = 0; index < sblock->page_count; index++) {
2291                         struct scrub_page *spage = sblock->pagev[index];
2292                         int ret;
2293
2294                         ret = scrub_add_page_to_rd_bio(sctx, spage);
2295                         if (ret) {
2296                                 scrub_block_put(sblock);
2297                                 return ret;
2298                         }
2299                 }
2300
2301                 if (force)
2302                         scrub_submit(sctx);
2303         }
2304
2305         /* last one frees, either here or in bio completion for last page */
2306         scrub_block_put(sblock);
2307         return 0;
2308 }
2309
2310 static void scrub_bio_end_io(struct bio *bio)
2311 {
2312         struct scrub_bio *sbio = bio->bi_private;
2313         struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
2314
2315         sbio->status = bio->bi_status;
2316         sbio->bio = bio;
2317
2318         btrfs_queue_work(fs_info->scrub_workers, &sbio->work);
2319 }
2320
2321 static void scrub_bio_end_io_worker(struct btrfs_work *work)
2322 {
2323         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
2324         struct scrub_ctx *sctx = sbio->sctx;
2325         int i;
2326
2327         BUG_ON(sbio->page_count > SCRUB_PAGES_PER_RD_BIO);
2328         if (sbio->status) {
2329                 for (i = 0; i < sbio->page_count; i++) {
2330                         struct scrub_page *spage = sbio->pagev[i];
2331
2332                         spage->io_error = 1;
2333                         spage->sblock->no_io_error_seen = 0;
2334                 }
2335         }
2336
2337         /* now complete the scrub_block items that have all pages completed */
2338         for (i = 0; i < sbio->page_count; i++) {
2339                 struct scrub_page *spage = sbio->pagev[i];
2340                 struct scrub_block *sblock = spage->sblock;
2341
2342                 if (atomic_dec_and_test(&sblock->outstanding_pages))
2343                         scrub_block_complete(sblock);
2344                 scrub_block_put(sblock);
2345         }
2346
2347         bio_put(sbio->bio);
2348         sbio->bio = NULL;
2349         spin_lock(&sctx->list_lock);
2350         sbio->next_free = sctx->first_free;
2351         sctx->first_free = sbio->index;
2352         spin_unlock(&sctx->list_lock);
2353
2354         if (sctx->is_dev_replace && sctx->flush_all_writes) {
2355                 mutex_lock(&sctx->wr_lock);
2356                 scrub_wr_submit(sctx);
2357                 mutex_unlock(&sctx->wr_lock);
2358         }
2359
2360         scrub_pending_bio_dec(sctx);
2361 }
2362
2363 static inline void __scrub_mark_bitmap(struct scrub_parity *sparity,
2364                                        unsigned long *bitmap,
2365                                        u64 start, u64 len)
2366 {
2367         u64 offset;
2368         u64 nsectors64;
2369         u32 nsectors;
2370         int sectorsize = sparity->sctx->fs_info->sectorsize;
2371
2372         if (len >= sparity->stripe_len) {
2373                 bitmap_set(bitmap, 0, sparity->nsectors);
2374                 return;
2375         }
2376
2377         start -= sparity->logic_start;
2378         start = div64_u64_rem(start, sparity->stripe_len, &offset);
2379         offset = div_u64(offset, sectorsize);
2380         nsectors64 = div_u64(len, sectorsize);
2381
2382         ASSERT(nsectors64 < UINT_MAX);
2383         nsectors = (u32)nsectors64;
2384
2385         if (offset + nsectors <= sparity->nsectors) {
2386                 bitmap_set(bitmap, offset, nsectors);
2387                 return;
2388         }
2389
2390         bitmap_set(bitmap, offset, sparity->nsectors - offset);
2391         bitmap_set(bitmap, 0, nsectors - (sparity->nsectors - offset));
2392 }
2393
2394 static inline void scrub_parity_mark_sectors_error(struct scrub_parity *sparity,
2395                                                    u64 start, u64 len)
2396 {
2397         __scrub_mark_bitmap(sparity, sparity->ebitmap, start, len);
2398 }
2399
2400 static inline void scrub_parity_mark_sectors_data(struct scrub_parity *sparity,
2401                                                   u64 start, u64 len)
2402 {
2403         __scrub_mark_bitmap(sparity, sparity->dbitmap, start, len);
2404 }
2405
2406 static void scrub_block_complete(struct scrub_block *sblock)
2407 {
2408         int corrupted = 0;
2409
2410         if (!sblock->no_io_error_seen) {
2411                 corrupted = 1;
2412                 scrub_handle_errored_block(sblock);
2413         } else {
2414                 /*
2415                  * if has checksum error, write via repair mechanism in
2416                  * dev replace case, otherwise write here in dev replace
2417                  * case.
2418                  */
2419                 corrupted = scrub_checksum(sblock);
2420                 if (!corrupted && sblock->sctx->is_dev_replace)
2421                         scrub_write_block_to_dev_replace(sblock);
2422         }
2423
2424         if (sblock->sparity && corrupted && !sblock->data_corrected) {
2425                 u64 start = sblock->pagev[0]->logical;
2426                 u64 end = sblock->pagev[sblock->page_count - 1]->logical +
2427                           PAGE_SIZE;
2428
2429                 scrub_parity_mark_sectors_error(sblock->sparity,
2430                                                 start, end - start);
2431         }
2432 }
2433
2434 static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u8 *csum)
2435 {
2436         struct btrfs_ordered_sum *sum = NULL;
2437         unsigned long index;
2438         unsigned long num_sectors;
2439
2440         while (!list_empty(&sctx->csum_list)) {
2441                 sum = list_first_entry(&sctx->csum_list,
2442                                        struct btrfs_ordered_sum, list);
2443                 if (sum->bytenr > logical)
2444                         return 0;
2445                 if (sum->bytenr + sum->len > logical)
2446                         break;
2447
2448                 ++sctx->stat.csum_discards;
2449                 list_del(&sum->list);
2450                 kfree(sum);
2451                 sum = NULL;
2452         }
2453         if (!sum)
2454                 return 0;
2455
2456         index = div_u64(logical - sum->bytenr, sctx->fs_info->sectorsize);
2457         ASSERT(index < UINT_MAX);
2458
2459         num_sectors = sum->len / sctx->fs_info->sectorsize;
2460         memcpy(csum, sum->sums + index * sctx->csum_size, sctx->csum_size);
2461         if (index == num_sectors - 1) {
2462                 list_del(&sum->list);
2463                 kfree(sum);
2464         }
2465         return 1;
2466 }
2467
2468 /* scrub extent tries to collect up to 64 kB for each bio */
2469 static int scrub_extent(struct scrub_ctx *sctx, struct map_lookup *map,
2470                         u64 logical, u64 len,
2471                         u64 physical, struct btrfs_device *dev, u64 flags,
2472                         u64 gen, int mirror_num, u64 physical_for_dev_replace)
2473 {
2474         int ret;
2475         u8 csum[BTRFS_CSUM_SIZE];
2476         u32 blocksize;
2477
2478         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2479                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
2480                         blocksize = map->stripe_len;
2481                 else
2482                         blocksize = sctx->fs_info->sectorsize;
2483                 spin_lock(&sctx->stat_lock);
2484                 sctx->stat.data_extents_scrubbed++;
2485                 sctx->stat.data_bytes_scrubbed += len;
2486                 spin_unlock(&sctx->stat_lock);
2487         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2488                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
2489                         blocksize = map->stripe_len;
2490                 else
2491                         blocksize = sctx->fs_info->nodesize;
2492                 spin_lock(&sctx->stat_lock);
2493                 sctx->stat.tree_extents_scrubbed++;
2494                 sctx->stat.tree_bytes_scrubbed += len;
2495                 spin_unlock(&sctx->stat_lock);
2496         } else {
2497                 blocksize = sctx->fs_info->sectorsize;
2498                 WARN_ON(1);
2499         }
2500
2501         while (len) {
2502                 u64 l = min_t(u64, len, blocksize);
2503                 int have_csum = 0;
2504
2505                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2506                         /* push csums to sbio */
2507                         have_csum = scrub_find_csum(sctx, logical, csum);
2508                         if (have_csum == 0)
2509                                 ++sctx->stat.no_csum;
2510                 }
2511                 ret = scrub_pages(sctx, logical, l, physical, dev, flags, gen,
2512                                   mirror_num, have_csum ? csum : NULL, 0,
2513                                   physical_for_dev_replace);
2514                 if (ret)
2515                         return ret;
2516                 len -= l;
2517                 logical += l;
2518                 physical += l;
2519                 physical_for_dev_replace += l;
2520         }
2521         return 0;
2522 }
2523
2524 static int scrub_pages_for_parity(struct scrub_parity *sparity,
2525                                   u64 logical, u64 len,
2526                                   u64 physical, struct btrfs_device *dev,
2527                                   u64 flags, u64 gen, int mirror_num, u8 *csum)
2528 {
2529         struct scrub_ctx *sctx = sparity->sctx;
2530         struct scrub_block *sblock;
2531         int index;
2532
2533         sblock = kzalloc(sizeof(*sblock), GFP_KERNEL);
2534         if (!sblock) {
2535                 spin_lock(&sctx->stat_lock);
2536                 sctx->stat.malloc_errors++;
2537                 spin_unlock(&sctx->stat_lock);
2538                 return -ENOMEM;
2539         }
2540
2541         /* one ref inside this function, plus one for each page added to
2542          * a bio later on */
2543         refcount_set(&sblock->refs, 1);
2544         sblock->sctx = sctx;
2545         sblock->no_io_error_seen = 1;
2546         sblock->sparity = sparity;
2547         scrub_parity_get(sparity);
2548
2549         for (index = 0; len > 0; index++) {
2550                 struct scrub_page *spage;
2551                 u64 l = min_t(u64, len, PAGE_SIZE);
2552
2553                 spage = kzalloc(sizeof(*spage), GFP_KERNEL);
2554                 if (!spage) {
2555 leave_nomem:
2556                         spin_lock(&sctx->stat_lock);
2557                         sctx->stat.malloc_errors++;
2558                         spin_unlock(&sctx->stat_lock);
2559                         scrub_block_put(sblock);
2560                         return -ENOMEM;
2561                 }
2562                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2563                 /* For scrub block */
2564                 scrub_page_get(spage);
2565                 sblock->pagev[index] = spage;
2566                 /* For scrub parity */
2567                 scrub_page_get(spage);
2568                 list_add_tail(&spage->list, &sparity->spages);
2569                 spage->sblock = sblock;
2570                 spage->dev = dev;
2571                 spage->flags = flags;
2572                 spage->generation = gen;
2573                 spage->logical = logical;
2574                 spage->physical = physical;
2575                 spage->mirror_num = mirror_num;
2576                 if (csum) {
2577                         spage->have_csum = 1;
2578                         memcpy(spage->csum, csum, sctx->csum_size);
2579                 } else {
2580                         spage->have_csum = 0;
2581                 }
2582                 sblock->page_count++;
2583                 spage->page = alloc_page(GFP_KERNEL);
2584                 if (!spage->page)
2585                         goto leave_nomem;
2586                 len -= l;
2587                 logical += l;
2588                 physical += l;
2589         }
2590
2591         WARN_ON(sblock->page_count == 0);
2592         for (index = 0; index < sblock->page_count; index++) {
2593                 struct scrub_page *spage = sblock->pagev[index];
2594                 int ret;
2595
2596                 ret = scrub_add_page_to_rd_bio(sctx, spage);
2597                 if (ret) {
2598                         scrub_block_put(sblock);
2599                         return ret;
2600                 }
2601         }
2602
2603         /* last one frees, either here or in bio completion for last page */
2604         scrub_block_put(sblock);
2605         return 0;
2606 }
2607
2608 static int scrub_extent_for_parity(struct scrub_parity *sparity,
2609                                    u64 logical, u64 len,
2610                                    u64 physical, struct btrfs_device *dev,
2611                                    u64 flags, u64 gen, int mirror_num)
2612 {
2613         struct scrub_ctx *sctx = sparity->sctx;
2614         int ret;
2615         u8 csum[BTRFS_CSUM_SIZE];
2616         u32 blocksize;
2617
2618         if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) {
2619                 scrub_parity_mark_sectors_error(sparity, logical, len);
2620                 return 0;
2621         }
2622
2623         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2624                 blocksize = sparity->stripe_len;
2625         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2626                 blocksize = sparity->stripe_len;
2627         } else {
2628                 blocksize = sctx->fs_info->sectorsize;
2629                 WARN_ON(1);
2630         }
2631
2632         while (len) {
2633                 u64 l = min_t(u64, len, blocksize);
2634                 int have_csum = 0;
2635
2636                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2637                         /* push csums to sbio */
2638                         have_csum = scrub_find_csum(sctx, logical, csum);
2639                         if (have_csum == 0)
2640                                 goto skip;
2641                 }
2642                 ret = scrub_pages_for_parity(sparity, logical, l, physical, dev,
2643                                              flags, gen, mirror_num,
2644                                              have_csum ? csum : NULL);
2645                 if (ret)
2646                         return ret;
2647 skip:
2648                 len -= l;
2649                 logical += l;
2650                 physical += l;
2651         }
2652         return 0;
2653 }
2654
2655 /*
2656  * Given a physical address, this will calculate it's
2657  * logical offset. if this is a parity stripe, it will return
2658  * the most left data stripe's logical offset.
2659  *
2660  * return 0 if it is a data stripe, 1 means parity stripe.
2661  */
2662 static int get_raid56_logic_offset(u64 physical, int num,
2663                                    struct map_lookup *map, u64 *offset,
2664                                    u64 *stripe_start)
2665 {
2666         int i;
2667         int j = 0;
2668         u64 stripe_nr;
2669         u64 last_offset;
2670         u32 stripe_index;
2671         u32 rot;
2672         const int data_stripes = nr_data_stripes(map);
2673
2674         last_offset = (physical - map->stripes[num].physical) * data_stripes;
2675         if (stripe_start)
2676                 *stripe_start = last_offset;
2677
2678         *offset = last_offset;
2679         for (i = 0; i < data_stripes; i++) {
2680                 *offset = last_offset + i * map->stripe_len;
2681
2682                 stripe_nr = div64_u64(*offset, map->stripe_len);
2683                 stripe_nr = div_u64(stripe_nr, data_stripes);
2684
2685                 /* Work out the disk rotation on this stripe-set */
2686                 stripe_nr = div_u64_rem(stripe_nr, map->num_stripes, &rot);
2687                 /* calculate which stripe this data locates */
2688                 rot += i;
2689                 stripe_index = rot % map->num_stripes;
2690                 if (stripe_index == num)
2691                         return 0;
2692                 if (stripe_index < num)
2693                         j++;
2694         }
2695         *offset = last_offset + j * map->stripe_len;
2696         return 1;
2697 }
2698
2699 static void scrub_free_parity(struct scrub_parity *sparity)
2700 {
2701         struct scrub_ctx *sctx = sparity->sctx;
2702         struct scrub_page *curr, *next;
2703         int nbits;
2704
2705         nbits = bitmap_weight(sparity->ebitmap, sparity->nsectors);
2706         if (nbits) {
2707                 spin_lock(&sctx->stat_lock);
2708                 sctx->stat.read_errors += nbits;
2709                 sctx->stat.uncorrectable_errors += nbits;
2710                 spin_unlock(&sctx->stat_lock);
2711         }
2712
2713         list_for_each_entry_safe(curr, next, &sparity->spages, list) {
2714                 list_del_init(&curr->list);
2715                 scrub_page_put(curr);
2716         }
2717
2718         kfree(sparity);
2719 }
2720
2721 static void scrub_parity_bio_endio_worker(struct btrfs_work *work)
2722 {
2723         struct scrub_parity *sparity = container_of(work, struct scrub_parity,
2724                                                     work);
2725         struct scrub_ctx *sctx = sparity->sctx;
2726
2727         scrub_free_parity(sparity);
2728         scrub_pending_bio_dec(sctx);
2729 }
2730
2731 static void scrub_parity_bio_endio(struct bio *bio)
2732 {
2733         struct scrub_parity *sparity = (struct scrub_parity *)bio->bi_private;
2734         struct btrfs_fs_info *fs_info = sparity->sctx->fs_info;
2735
2736         if (bio->bi_status)
2737                 bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
2738                           sparity->nsectors);
2739
2740         bio_put(bio);
2741
2742         btrfs_init_work(&sparity->work, scrub_parity_bio_endio_worker, NULL,
2743                         NULL);
2744         btrfs_queue_work(fs_info->scrub_parity_workers, &sparity->work);
2745 }
2746
2747 static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
2748 {
2749         struct scrub_ctx *sctx = sparity->sctx;
2750         struct btrfs_fs_info *fs_info = sctx->fs_info;
2751         struct bio *bio;
2752         struct btrfs_raid_bio *rbio;
2753         struct btrfs_bio *bbio = NULL;
2754         u64 length;
2755         int ret;
2756
2757         if (!bitmap_andnot(sparity->dbitmap, sparity->dbitmap, sparity->ebitmap,
2758                            sparity->nsectors))
2759                 goto out;
2760
2761         length = sparity->logic_end - sparity->logic_start;
2762
2763         btrfs_bio_counter_inc_blocked(fs_info);
2764         ret = btrfs_map_sblock(fs_info, BTRFS_MAP_WRITE, sparity->logic_start,
2765                                &length, &bbio);
2766         if (ret || !bbio || !bbio->raid_map)
2767                 goto bbio_out;
2768
2769         bio = btrfs_io_bio_alloc(0);
2770         bio->bi_iter.bi_sector = sparity->logic_start >> 9;
2771         bio->bi_private = sparity;
2772         bio->bi_end_io = scrub_parity_bio_endio;
2773
2774         rbio = raid56_parity_alloc_scrub_rbio(fs_info, bio, bbio,
2775                                               length, sparity->scrub_dev,
2776                                               sparity->dbitmap,
2777                                               sparity->nsectors);
2778         if (!rbio)
2779                 goto rbio_out;
2780
2781         scrub_pending_bio_inc(sctx);
2782         raid56_parity_submit_scrub_rbio(rbio);
2783         return;
2784
2785 rbio_out:
2786         bio_put(bio);
2787 bbio_out:
2788         btrfs_bio_counter_dec(fs_info);
2789         btrfs_put_bbio(bbio);
2790         bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
2791                   sparity->nsectors);
2792         spin_lock(&sctx->stat_lock);
2793         sctx->stat.malloc_errors++;
2794         spin_unlock(&sctx->stat_lock);
2795 out:
2796         scrub_free_parity(sparity);
2797 }
2798
2799 static inline int scrub_calc_parity_bitmap_len(int nsectors)
2800 {
2801         return DIV_ROUND_UP(nsectors, BITS_PER_LONG) * sizeof(long);
2802 }
2803
2804 static void scrub_parity_get(struct scrub_parity *sparity)
2805 {
2806         refcount_inc(&sparity->refs);
2807 }
2808
2809 static void scrub_parity_put(struct scrub_parity *sparity)
2810 {
2811         if (!refcount_dec_and_test(&sparity->refs))
2812                 return;
2813
2814         scrub_parity_check_and_repair(sparity);
2815 }
2816
2817 static noinline_for_stack int scrub_raid56_parity(struct scrub_ctx *sctx,
2818                                                   struct map_lookup *map,
2819                                                   struct btrfs_device *sdev,
2820                                                   struct btrfs_path *path,
2821                                                   u64 logic_start,
2822                                                   u64 logic_end)
2823 {
2824         struct btrfs_fs_info *fs_info = sctx->fs_info;
2825         struct btrfs_root *root = fs_info->extent_root;
2826         struct btrfs_root *csum_root = fs_info->csum_root;
2827         struct btrfs_extent_item *extent;
2828         struct btrfs_bio *bbio = NULL;
2829         u64 flags;
2830         int ret;
2831         int slot;
2832         struct extent_buffer *l;
2833         struct btrfs_key key;
2834         u64 generation;
2835         u64 extent_logical;
2836         u64 extent_physical;
2837         u64 extent_len;
2838         u64 mapped_length;
2839         struct btrfs_device *extent_dev;
2840         struct scrub_parity *sparity;
2841         int nsectors;
2842         int bitmap_len;
2843         int extent_mirror_num;
2844         int stop_loop = 0;
2845
2846         nsectors = div_u64(map->stripe_len, fs_info->sectorsize);
2847         bitmap_len = scrub_calc_parity_bitmap_len(nsectors);
2848         sparity = kzalloc(sizeof(struct scrub_parity) + 2 * bitmap_len,
2849                           GFP_NOFS);
2850         if (!sparity) {
2851                 spin_lock(&sctx->stat_lock);
2852                 sctx->stat.malloc_errors++;
2853                 spin_unlock(&sctx->stat_lock);
2854                 return -ENOMEM;
2855         }
2856
2857         sparity->stripe_len = map->stripe_len;
2858         sparity->nsectors = nsectors;
2859         sparity->sctx = sctx;
2860         sparity->scrub_dev = sdev;
2861         sparity->logic_start = logic_start;
2862         sparity->logic_end = logic_end;
2863         refcount_set(&sparity->refs, 1);
2864         INIT_LIST_HEAD(&sparity->spages);
2865         sparity->dbitmap = sparity->bitmap;
2866         sparity->ebitmap = (void *)sparity->bitmap + bitmap_len;
2867
2868         ret = 0;
2869         while (logic_start < logic_end) {
2870                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
2871                         key.type = BTRFS_METADATA_ITEM_KEY;
2872                 else
2873                         key.type = BTRFS_EXTENT_ITEM_KEY;
2874                 key.objectid = logic_start;
2875                 key.offset = (u64)-1;
2876
2877                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2878                 if (ret < 0)
2879                         goto out;
2880
2881                 if (ret > 0) {
2882                         ret = btrfs_previous_extent_item(root, path, 0);
2883                         if (ret < 0)
2884                                 goto out;
2885                         if (ret > 0) {
2886                                 btrfs_release_path(path);
2887                                 ret = btrfs_search_slot(NULL, root, &key,
2888                                                         path, 0, 0);
2889                                 if (ret < 0)
2890                                         goto out;
2891                         }
2892                 }
2893
2894                 stop_loop = 0;
2895                 while (1) {
2896                         u64 bytes;
2897
2898                         l = path->nodes[0];
2899                         slot = path->slots[0];
2900                         if (slot >= btrfs_header_nritems(l)) {
2901                                 ret = btrfs_next_leaf(root, path);
2902                                 if (ret == 0)
2903                                         continue;
2904                                 if (ret < 0)
2905                                         goto out;
2906
2907                                 stop_loop = 1;
2908                                 break;
2909                         }
2910                         btrfs_item_key_to_cpu(l, &key, slot);
2911
2912                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
2913                             key.type != BTRFS_METADATA_ITEM_KEY)
2914                                 goto next;
2915
2916                         if (key.type == BTRFS_METADATA_ITEM_KEY)
2917                                 bytes = fs_info->nodesize;
2918                         else
2919                                 bytes = key.offset;
2920
2921                         if (key.objectid + bytes <= logic_start)
2922                                 goto next;
2923
2924                         if (key.objectid >= logic_end) {
2925                                 stop_loop = 1;
2926                                 break;
2927                         }
2928
2929                         while (key.objectid >= logic_start + map->stripe_len)
2930                                 logic_start += map->stripe_len;
2931
2932                         extent = btrfs_item_ptr(l, slot,
2933                                                 struct btrfs_extent_item);
2934                         flags = btrfs_extent_flags(l, extent);
2935                         generation = btrfs_extent_generation(l, extent);
2936
2937                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
2938                             (key.objectid < logic_start ||
2939                              key.objectid + bytes >
2940                              logic_start + map->stripe_len)) {
2941                                 btrfs_err(fs_info,
2942                                           "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
2943                                           key.objectid, logic_start);
2944                                 spin_lock(&sctx->stat_lock);
2945                                 sctx->stat.uncorrectable_errors++;
2946                                 spin_unlock(&sctx->stat_lock);
2947                                 goto next;
2948                         }
2949 again:
2950                         extent_logical = key.objectid;
2951                         extent_len = bytes;
2952
2953                         if (extent_logical < logic_start) {
2954                                 extent_len -= logic_start - extent_logical;
2955                                 extent_logical = logic_start;
2956                         }
2957
2958                         if (extent_logical + extent_len >
2959                             logic_start + map->stripe_len)
2960                                 extent_len = logic_start + map->stripe_len -
2961                                              extent_logical;
2962
2963                         scrub_parity_mark_sectors_data(sparity, extent_logical,
2964                                                        extent_len);
2965
2966                         mapped_length = extent_len;
2967                         bbio = NULL;
2968                         ret = btrfs_map_block(fs_info, BTRFS_MAP_READ,
2969                                         extent_logical, &mapped_length, &bbio,
2970                                         0);
2971                         if (!ret) {
2972                                 if (!bbio || mapped_length < extent_len)
2973                                         ret = -EIO;
2974                         }
2975                         if (ret) {
2976                                 btrfs_put_bbio(bbio);
2977                                 goto out;
2978                         }
2979                         extent_physical = bbio->stripes[0].physical;
2980                         extent_mirror_num = bbio->mirror_num;
2981                         extent_dev = bbio->stripes[0].dev;
2982                         btrfs_put_bbio(bbio);
2983
2984                         ret = btrfs_lookup_csums_range(csum_root,
2985                                                 extent_logical,
2986                                                 extent_logical + extent_len - 1,
2987                                                 &sctx->csum_list, 1);
2988                         if (ret)
2989                                 goto out;
2990
2991                         ret = scrub_extent_for_parity(sparity, extent_logical,
2992                                                       extent_len,
2993                                                       extent_physical,
2994                                                       extent_dev, flags,
2995                                                       generation,
2996                                                       extent_mirror_num);
2997
2998                         scrub_free_csums(sctx);
2999
3000                         if (ret)
3001                                 goto out;
3002
3003                         if (extent_logical + extent_len <
3004                             key.objectid + bytes) {
3005                                 logic_start += map->stripe_len;
3006
3007                                 if (logic_start >= logic_end) {
3008                                         stop_loop = 1;
3009                                         break;
3010                                 }
3011
3012                                 if (logic_start < key.objectid + bytes) {
3013                                         cond_resched();
3014                                         goto again;
3015                                 }
3016                         }
3017 next:
3018                         path->slots[0]++;
3019                 }
3020
3021                 btrfs_release_path(path);
3022
3023                 if (stop_loop)
3024                         break;
3025
3026                 logic_start += map->stripe_len;
3027         }
3028 out:
3029         if (ret < 0)
3030                 scrub_parity_mark_sectors_error(sparity, logic_start,
3031                                                 logic_end - logic_start);
3032         scrub_parity_put(sparity);
3033         scrub_submit(sctx);
3034         mutex_lock(&sctx->wr_lock);
3035         scrub_wr_submit(sctx);
3036         mutex_unlock(&sctx->wr_lock);
3037
3038         btrfs_release_path(path);
3039         return ret < 0 ? ret : 0;
3040 }
3041
3042 static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
3043                                            struct map_lookup *map,
3044                                            struct btrfs_device *scrub_dev,
3045                                            int num, u64 base, u64 length)
3046 {
3047         struct btrfs_path *path, *ppath;
3048         struct btrfs_fs_info *fs_info = sctx->fs_info;
3049         struct btrfs_root *root = fs_info->extent_root;
3050         struct btrfs_root *csum_root = fs_info->csum_root;
3051         struct btrfs_extent_item *extent;
3052         struct blk_plug plug;
3053         u64 flags;
3054         int ret;
3055         int slot;
3056         u64 nstripes;
3057         struct extent_buffer *l;
3058         u64 physical;
3059         u64 logical;
3060         u64 logic_end;
3061         u64 physical_end;
3062         u64 generation;
3063         int mirror_num;
3064         struct reada_control *reada1;
3065         struct reada_control *reada2;
3066         struct btrfs_key key;
3067         struct btrfs_key key_end;
3068         u64 increment = map->stripe_len;
3069         u64 offset;
3070         u64 extent_logical;
3071         u64 extent_physical;
3072         u64 extent_len;
3073         u64 stripe_logical;
3074         u64 stripe_end;
3075         struct btrfs_device *extent_dev;
3076         int extent_mirror_num;
3077         int stop_loop = 0;
3078
3079         physical = map->stripes[num].physical;
3080         offset = 0;
3081         nstripes = div64_u64(length, map->stripe_len);
3082         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
3083                 offset = map->stripe_len * num;
3084                 increment = map->stripe_len * map->num_stripes;
3085                 mirror_num = 1;
3086         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
3087                 int factor = map->num_stripes / map->sub_stripes;
3088                 offset = map->stripe_len * (num / map->sub_stripes);
3089                 increment = map->stripe_len * factor;
3090                 mirror_num = num % map->sub_stripes + 1;
3091         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1_MASK) {
3092                 increment = map->stripe_len;
3093                 mirror_num = num % map->num_stripes + 1;
3094         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
3095                 increment = map->stripe_len;
3096                 mirror_num = num % map->num_stripes + 1;
3097         } else if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3098                 get_raid56_logic_offset(physical, num, map, &offset, NULL);
3099                 increment = map->stripe_len * nr_data_stripes(map);
3100                 mirror_num = 1;
3101         } else {
3102                 increment = map->stripe_len;
3103                 mirror_num = 1;
3104         }
3105
3106         path = btrfs_alloc_path();
3107         if (!path)
3108                 return -ENOMEM;
3109
3110         ppath = btrfs_alloc_path();
3111         if (!ppath) {
3112                 btrfs_free_path(path);
3113                 return -ENOMEM;
3114         }
3115
3116         /*
3117          * work on commit root. The related disk blocks are static as
3118          * long as COW is applied. This means, it is save to rewrite
3119          * them to repair disk errors without any race conditions
3120          */
3121         path->search_commit_root = 1;
3122         path->skip_locking = 1;
3123
3124         ppath->search_commit_root = 1;
3125         ppath->skip_locking = 1;
3126         /*
3127          * trigger the readahead for extent tree csum tree and wait for
3128          * completion. During readahead, the scrub is officially paused
3129          * to not hold off transaction commits
3130          */
3131         logical = base + offset;
3132         physical_end = physical + nstripes * map->stripe_len;
3133         if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3134                 get_raid56_logic_offset(physical_end, num,
3135                                         map, &logic_end, NULL);
3136                 logic_end += base;
3137         } else {
3138                 logic_end = logical + increment * nstripes;
3139         }
3140         wait_event(sctx->list_wait,
3141                    atomic_read(&sctx->bios_in_flight) == 0);
3142         scrub_blocked_if_needed(fs_info);
3143
3144         /* FIXME it might be better to start readahead at commit root */
3145         key.objectid = logical;
3146         key.type = BTRFS_EXTENT_ITEM_KEY;
3147         key.offset = (u64)0;
3148         key_end.objectid = logic_end;
3149         key_end.type = BTRFS_METADATA_ITEM_KEY;
3150         key_end.offset = (u64)-1;
3151         reada1 = btrfs_reada_add(root, &key, &key_end);
3152
3153         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3154         key.type = BTRFS_EXTENT_CSUM_KEY;
3155         key.offset = logical;
3156         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
3157         key_end.type = BTRFS_EXTENT_CSUM_KEY;
3158         key_end.offset = logic_end;
3159         reada2 = btrfs_reada_add(csum_root, &key, &key_end);
3160
3161         if (!IS_ERR(reada1))
3162                 btrfs_reada_wait(reada1);
3163         if (!IS_ERR(reada2))
3164                 btrfs_reada_wait(reada2);
3165
3166
3167         /*
3168          * collect all data csums for the stripe to avoid seeking during
3169          * the scrub. This might currently (crc32) end up to be about 1MB
3170          */
3171         blk_start_plug(&plug);
3172
3173         /*
3174          * now find all extents for each stripe and scrub them
3175          */
3176         ret = 0;
3177         while (physical < physical_end) {
3178                 /*
3179                  * canceled?
3180                  */
3181                 if (atomic_read(&fs_info->scrub_cancel_req) ||
3182                     atomic_read(&sctx->cancel_req)) {
3183                         ret = -ECANCELED;
3184                         goto out;
3185                 }
3186                 /*
3187                  * check to see if we have to pause
3188                  */
3189                 if (atomic_read(&fs_info->scrub_pause_req)) {
3190                         /* push queued extents */
3191                         sctx->flush_all_writes = true;
3192                         scrub_submit(sctx);
3193                         mutex_lock(&sctx->wr_lock);
3194                         scrub_wr_submit(sctx);
3195                         mutex_unlock(&sctx->wr_lock);
3196                         wait_event(sctx->list_wait,
3197                                    atomic_read(&sctx->bios_in_flight) == 0);
3198                         sctx->flush_all_writes = false;
3199                         scrub_blocked_if_needed(fs_info);
3200                 }
3201
3202                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3203                         ret = get_raid56_logic_offset(physical, num, map,
3204                                                       &logical,
3205                                                       &stripe_logical);
3206                         logical += base;
3207                         if (ret) {
3208                                 /* it is parity strip */
3209                                 stripe_logical += base;
3210                                 stripe_end = stripe_logical + increment;
3211                                 ret = scrub_raid56_parity(sctx, map, scrub_dev,
3212                                                           ppath, stripe_logical,
3213                                                           stripe_end);
3214                                 if (ret)
3215                                         goto out;
3216                                 goto skip;
3217                         }
3218                 }
3219
3220                 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
3221                         key.type = BTRFS_METADATA_ITEM_KEY;
3222                 else
3223                         key.type = BTRFS_EXTENT_ITEM_KEY;
3224                 key.objectid = logical;
3225                 key.offset = (u64)-1;
3226
3227                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3228                 if (ret < 0)
3229                         goto out;
3230
3231                 if (ret > 0) {
3232                         ret = btrfs_previous_extent_item(root, path, 0);
3233                         if (ret < 0)
3234                                 goto out;
3235                         if (ret > 0) {
3236                                 /* there's no smaller item, so stick with the
3237                                  * larger one */
3238                                 btrfs_release_path(path);
3239                                 ret = btrfs_search_slot(NULL, root, &key,
3240                                                         path, 0, 0);
3241                                 if (ret < 0)
3242                                         goto out;
3243                         }
3244                 }
3245
3246                 stop_loop = 0;
3247                 while (1) {
3248                         u64 bytes;
3249
3250                         l = path->nodes[0];
3251                         slot = path->slots[0];
3252                         if (slot >= btrfs_header_nritems(l)) {
3253                                 ret = btrfs_next_leaf(root, path);
3254                                 if (ret == 0)
3255                                         continue;
3256                                 if (ret < 0)
3257                                         goto out;
3258
3259                                 stop_loop = 1;
3260                                 break;
3261                         }
3262                         btrfs_item_key_to_cpu(l, &key, slot);
3263
3264                         if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3265                             key.type != BTRFS_METADATA_ITEM_KEY)
3266                                 goto next;
3267
3268                         if (key.type == BTRFS_METADATA_ITEM_KEY)
3269                                 bytes = fs_info->nodesize;
3270                         else
3271                                 bytes = key.offset;
3272
3273                         if (key.objectid + bytes <= logical)
3274                                 goto next;
3275
3276                         if (key.objectid >= logical + map->stripe_len) {
3277                                 /* out of this device extent */
3278                                 if (key.objectid >= logic_end)
3279                                         stop_loop = 1;
3280                                 break;
3281                         }
3282
3283                         extent = btrfs_item_ptr(l, slot,
3284                                                 struct btrfs_extent_item);
3285                         flags = btrfs_extent_flags(l, extent);
3286                         generation = btrfs_extent_generation(l, extent);
3287
3288                         if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) &&
3289                             (key.objectid < logical ||
3290                              key.objectid + bytes >
3291                              logical + map->stripe_len)) {
3292                                 btrfs_err(fs_info,
3293                                            "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
3294                                        key.objectid, logical);
3295                                 spin_lock(&sctx->stat_lock);
3296                                 sctx->stat.uncorrectable_errors++;
3297                                 spin_unlock(&sctx->stat_lock);
3298                                 goto next;
3299                         }
3300
3301 again:
3302                         extent_logical = key.objectid;
3303                         extent_len = bytes;
3304
3305                         /*
3306                          * trim extent to this stripe
3307                          */
3308                         if (extent_logical < logical) {
3309                                 extent_len -= logical - extent_logical;
3310                                 extent_logical = logical;
3311                         }
3312                         if (extent_logical + extent_len >
3313                             logical + map->stripe_len) {
3314                                 extent_len = logical + map->stripe_len -
3315                                              extent_logical;
3316                         }
3317
3318                         extent_physical = extent_logical - logical + physical;
3319                         extent_dev = scrub_dev;
3320                         extent_mirror_num = mirror_num;
3321                         if (sctx->is_dev_replace)
3322                                 scrub_remap_extent(fs_info, extent_logical,
3323                                                    extent_len, &extent_physical,
3324                                                    &extent_dev,
3325                                                    &extent_mirror_num);
3326
3327                         ret = btrfs_lookup_csums_range(csum_root,
3328                                                        extent_logical,
3329                                                        extent_logical +
3330                                                        extent_len - 1,
3331                                                        &sctx->csum_list, 1);
3332                         if (ret)
3333                                 goto out;
3334
3335                         ret = scrub_extent(sctx, map, extent_logical, extent_len,
3336                                            extent_physical, extent_dev, flags,
3337                                            generation, extent_mirror_num,
3338                                            extent_logical - logical + physical);
3339
3340                         scrub_free_csums(sctx);
3341
3342                         if (ret)
3343                                 goto out;
3344
3345                         if (extent_logical + extent_len <
3346                             key.objectid + bytes) {
3347                                 if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
3348                                         /*
3349                                          * loop until we find next data stripe
3350                                          * or we have finished all stripes.
3351                                          */
3352 loop:
3353                                         physical += map->stripe_len;
3354                                         ret = get_raid56_logic_offset(physical,
3355                                                         num, map, &logical,
3356                                                         &stripe_logical);
3357                                         logical += base;
3358
3359                                         if (ret && physical < physical_end) {
3360                                                 stripe_logical += base;
3361                                                 stripe_end = stripe_logical +
3362                                                                 increment;
3363                                                 ret = scrub_raid56_parity(sctx,
3364                                                         map, scrub_dev, ppath,
3365                                                         stripe_logical,
3366                                                         stripe_end);
3367                                                 if (ret)
3368                                                         goto out;
3369                                                 goto loop;
3370                                         }
3371                                 } else {
3372                                         physical += map->stripe_len;
3373                                         logical += increment;
3374                                 }
3375                                 if (logical < key.objectid + bytes) {
3376                                         cond_resched();
3377                                         goto again;
3378                                 }
3379
3380                                 if (physical >= physical_end) {
3381                                         stop_loop = 1;
3382                                         break;
3383                                 }
3384                         }
3385 next:
3386                         path->slots[0]++;
3387                 }
3388                 btrfs_release_path(path);
3389 skip:
3390                 logical += increment;
3391                 physical += map->stripe_len;
3392                 spin_lock(&sctx->stat_lock);
3393                 if (stop_loop)
3394                         sctx->stat.last_physical = map->stripes[num].physical +
3395                                                    length;
3396                 else
3397                         sctx->stat.last_physical = physical;
3398                 spin_unlock(&sctx->stat_lock);
3399                 if (stop_loop)
3400                         break;
3401         }
3402 out:
3403         /* push queued extents */
3404         scrub_submit(sctx);
3405         mutex_lock(&sctx->wr_lock);
3406         scrub_wr_submit(sctx);
3407         mutex_unlock(&sctx->wr_lock);
3408
3409         blk_finish_plug(&plug);
3410         btrfs_free_path(path);
3411         btrfs_free_path(ppath);
3412         return ret < 0 ? ret : 0;
3413 }
3414
3415 static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
3416                                           struct btrfs_device *scrub_dev,
3417                                           u64 chunk_offset, u64 length,
3418                                           u64 dev_offset,
3419                                           struct btrfs_block_group *cache)
3420 {
3421         struct btrfs_fs_info *fs_info = sctx->fs_info;
3422         struct extent_map_tree *map_tree = &fs_info->mapping_tree;
3423         struct map_lookup *map;
3424         struct extent_map *em;
3425         int i;
3426         int ret = 0;
3427
3428         read_lock(&map_tree->lock);
3429         em = lookup_extent_mapping(map_tree, chunk_offset, 1);
3430         read_unlock(&map_tree->lock);
3431
3432         if (!em) {
3433                 /*
3434                  * Might have been an unused block group deleted by the cleaner
3435                  * kthread or relocation.
3436                  */
3437                 spin_lock(&cache->lock);
3438                 if (!cache->removed)
3439                         ret = -EINVAL;
3440                 spin_unlock(&cache->lock);
3441
3442                 return ret;
3443         }
3444
3445         map = em->map_lookup;
3446         if (em->start != chunk_offset)
3447                 goto out;
3448
3449         if (em->len < length)
3450                 goto out;
3451
3452         for (i = 0; i < map->num_stripes; ++i) {
3453                 if (map->stripes[i].dev->bdev == scrub_dev->bdev &&
3454                     map->stripes[i].physical == dev_offset) {
3455                         ret = scrub_stripe(sctx, map, scrub_dev, i,
3456                                            chunk_offset, length);
3457                         if (ret)
3458                                 goto out;
3459                 }
3460         }
3461 out:
3462         free_extent_map(em);
3463
3464         return ret;
3465 }
3466
3467 static noinline_for_stack
3468 int scrub_enumerate_chunks(struct scrub_ctx *sctx,
3469                            struct btrfs_device *scrub_dev, u64 start, u64 end)
3470 {
3471         struct btrfs_dev_extent *dev_extent = NULL;
3472         struct btrfs_path *path;
3473         struct btrfs_fs_info *fs_info = sctx->fs_info;
3474         struct btrfs_root *root = fs_info->dev_root;
3475         u64 length;
3476         u64 chunk_offset;
3477         int ret = 0;
3478         int ro_set;
3479         int slot;
3480         struct extent_buffer *l;
3481         struct btrfs_key key;
3482         struct btrfs_key found_key;
3483         struct btrfs_block_group *cache;
3484         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
3485
3486         path = btrfs_alloc_path();
3487         if (!path)
3488                 return -ENOMEM;
3489
3490         path->reada = READA_FORWARD;
3491         path->search_commit_root = 1;
3492         path->skip_locking = 1;
3493
3494         key.objectid = scrub_dev->devid;
3495         key.offset = 0ull;
3496         key.type = BTRFS_DEV_EXTENT_KEY;
3497
3498         while (1) {
3499                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3500                 if (ret < 0)
3501                         break;
3502                 if (ret > 0) {
3503                         if (path->slots[0] >=
3504                             btrfs_header_nritems(path->nodes[0])) {
3505                                 ret = btrfs_next_leaf(root, path);
3506                                 if (ret < 0)
3507                                         break;
3508                                 if (ret > 0) {
3509                                         ret = 0;
3510                                         break;
3511                                 }
3512                         } else {
3513                                 ret = 0;
3514                         }
3515                 }
3516
3517                 l = path->nodes[0];
3518                 slot = path->slots[0];
3519
3520                 btrfs_item_key_to_cpu(l, &found_key, slot);
3521
3522                 if (found_key.objectid != scrub_dev->devid)
3523                         break;
3524
3525                 if (found_key.type != BTRFS_DEV_EXTENT_KEY)
3526                         break;
3527
3528                 if (found_key.offset >= end)
3529                         break;
3530
3531                 if (found_key.offset < key.offset)
3532                         break;
3533
3534                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
3535                 length = btrfs_dev_extent_length(l, dev_extent);
3536
3537                 if (found_key.offset + length <= start)
3538                         goto skip;
3539
3540                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
3541
3542                 /*
3543                  * get a reference on the corresponding block group to prevent
3544                  * the chunk from going away while we scrub it
3545                  */
3546                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
3547
3548                 /* some chunks are removed but not committed to disk yet,
3549                  * continue scrubbing */
3550                 if (!cache)
3551                         goto skip;
3552
3553                 /*
3554                  * we need call btrfs_inc_block_group_ro() with scrubs_paused,
3555                  * to avoid deadlock caused by:
3556                  * btrfs_inc_block_group_ro()
3557                  * -> btrfs_wait_for_commit()
3558                  * -> btrfs_commit_transaction()
3559                  * -> btrfs_scrub_pause()
3560                  */
3561                 scrub_pause_on(fs_info);
3562
3563                 /*
3564                  * Don't do chunk preallocation for scrub.
3565                  *
3566                  * This is especially important for SYSTEM bgs, or we can hit
3567                  * -EFBIG from btrfs_finish_chunk_alloc() like:
3568                  * 1. The only SYSTEM bg is marked RO.
3569                  *    Since SYSTEM bg is small, that's pretty common.
3570                  * 2. New SYSTEM bg will be allocated
3571                  *    Due to regular version will allocate new chunk.
3572                  * 3. New SYSTEM bg is empty and will get cleaned up
3573                  *    Before cleanup really happens, it's marked RO again.
3574                  * 4. Empty SYSTEM bg get scrubbed
3575                  *    We go back to 2.
3576                  *
3577                  * This can easily boost the amount of SYSTEM chunks if cleaner
3578                  * thread can't be triggered fast enough, and use up all space
3579                  * of btrfs_super_block::sys_chunk_array
3580                  *
3581                  * While for dev replace, we need to try our best to mark block
3582                  * group RO, to prevent race between:
3583                  * - Write duplication
3584                  *   Contains latest data
3585                  * - Scrub copy
3586                  *   Contains data from commit tree
3587                  *
3588                  * If target block group is not marked RO, nocow writes can
3589                  * be overwritten by scrub copy, causing data corruption.
3590                  * So for dev-replace, it's not allowed to continue if a block
3591                  * group is not RO.
3592                  */
3593                 ret = btrfs_inc_block_group_ro(cache, sctx->is_dev_replace);
3594                 if (ret == 0) {
3595                         ro_set = 1;
3596                 } else if (ret == -ENOSPC && !sctx->is_dev_replace) {
3597                         /*
3598                          * btrfs_inc_block_group_ro return -ENOSPC when it
3599                          * failed in creating new chunk for metadata.
3600                          * It is not a problem for scrub, because
3601                          * metadata are always cowed, and our scrub paused
3602                          * commit_transactions.
3603                          */
3604                         ro_set = 0;
3605                 } else {
3606                         btrfs_warn(fs_info,
3607                                    "failed setting block group ro: %d", ret);
3608                         btrfs_put_block_group(cache);
3609                         scrub_pause_off(fs_info);
3610                         break;
3611                 }
3612
3613                 /*
3614                  * Now the target block is marked RO, wait for nocow writes to
3615                  * finish before dev-replace.
3616                  * COW is fine, as COW never overwrites extents in commit tree.
3617                  */
3618                 if (sctx->is_dev_replace) {
3619                         btrfs_wait_nocow_writers(cache);
3620                         btrfs_wait_ordered_roots(fs_info, U64_MAX, cache->start,
3621                                         cache->length);
3622                 }
3623
3624                 scrub_pause_off(fs_info);
3625                 down_write(&dev_replace->rwsem);
3626                 dev_replace->cursor_right = found_key.offset + length;
3627                 dev_replace->cursor_left = found_key.offset;
3628                 dev_replace->item_needs_writeback = 1;
3629                 up_write(&dev_replace->rwsem);
3630
3631                 ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length,
3632                                   found_key.offset, cache);
3633
3634                 /*
3635                  * flush, submit all pending read and write bios, afterwards
3636                  * wait for them.
3637                  * Note that in the dev replace case, a read request causes
3638                  * write requests that are submitted in the read completion
3639                  * worker. Therefore in the current situation, it is required
3640                  * that all write requests are flushed, so that all read and
3641                  * write requests are really completed when bios_in_flight
3642                  * changes to 0.
3643                  */
3644                 sctx->flush_all_writes = true;
3645                 scrub_submit(sctx);
3646                 mutex_lock(&sctx->wr_lock);
3647                 scrub_wr_submit(sctx);
3648                 mutex_unlock(&sctx->wr_lock);
3649
3650                 wait_event(sctx->list_wait,
3651                            atomic_read(&sctx->bios_in_flight) == 0);
3652
3653                 scrub_pause_on(fs_info);
3654
3655                 /*
3656                  * must be called before we decrease @scrub_paused.
3657                  * make sure we don't block transaction commit while
3658                  * we are waiting pending workers finished.
3659                  */
3660                 wait_event(sctx->list_wait,
3661                            atomic_read(&sctx->workers_pending) == 0);
3662                 sctx->flush_all_writes = false;
3663
3664                 scrub_pause_off(fs_info);
3665
3666                 down_write(&dev_replace->rwsem);
3667                 dev_replace->cursor_left = dev_replace->cursor_right;
3668                 dev_replace->item_needs_writeback = 1;
3669                 up_write(&dev_replace->rwsem);
3670
3671                 if (ro_set)
3672                         btrfs_dec_block_group_ro(cache);
3673
3674                 /*
3675                  * We might have prevented the cleaner kthread from deleting
3676                  * this block group if it was already unused because we raced
3677                  * and set it to RO mode first. So add it back to the unused
3678                  * list, otherwise it might not ever be deleted unless a manual
3679                  * balance is triggered or it becomes used and unused again.
3680                  */
3681                 spin_lock(&cache->lock);
3682                 if (!cache->removed && !cache->ro && cache->reserved == 0 &&
3683                     cache->used == 0) {
3684                         spin_unlock(&cache->lock);
3685                         btrfs_mark_bg_unused(cache);
3686                 } else {
3687                         spin_unlock(&cache->lock);
3688                 }
3689
3690                 btrfs_put_block_group(cache);
3691                 if (ret)
3692                         break;
3693                 if (sctx->is_dev_replace &&
3694                     atomic64_read(&dev_replace->num_write_errors) > 0) {
3695                         ret = -EIO;
3696                         break;
3697                 }
3698                 if (sctx->stat.malloc_errors > 0) {
3699                         ret = -ENOMEM;
3700                         break;
3701                 }
3702 skip:
3703                 key.offset = found_key.offset + length;
3704                 btrfs_release_path(path);
3705         }
3706
3707         btrfs_free_path(path);
3708
3709         return ret;
3710 }
3711
3712 static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
3713                                            struct btrfs_device *scrub_dev)
3714 {
3715         int     i;
3716         u64     bytenr;
3717         u64     gen;
3718         int     ret;
3719         struct btrfs_fs_info *fs_info = sctx->fs_info;
3720
3721         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
3722                 return -EIO;
3723
3724         /* Seed devices of a new filesystem has their own generation. */
3725         if (scrub_dev->fs_devices != fs_info->fs_devices)
3726                 gen = scrub_dev->generation;
3727         else
3728                 gen = fs_info->last_trans_committed;
3729
3730         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
3731                 bytenr = btrfs_sb_offset(i);
3732                 if (bytenr + BTRFS_SUPER_INFO_SIZE >
3733                     scrub_dev->commit_total_bytes)
3734                         break;
3735
3736                 ret = scrub_pages(sctx, bytenr, BTRFS_SUPER_INFO_SIZE, bytenr,
3737                                   scrub_dev, BTRFS_EXTENT_FLAG_SUPER, gen, i,
3738                                   NULL, 1, bytenr);
3739                 if (ret)
3740                         return ret;
3741         }
3742         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
3743
3744         return 0;
3745 }
3746
3747 /*
3748  * get a reference count on fs_info->scrub_workers. start worker if necessary
3749  */
3750 static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
3751                                                 int is_dev_replace)
3752 {
3753         unsigned int flags = WQ_FREEZABLE | WQ_UNBOUND;
3754         int max_active = fs_info->thread_pool_size;
3755
3756         lockdep_assert_held(&fs_info->scrub_lock);
3757
3758         if (refcount_read(&fs_info->scrub_workers_refcnt) == 0) {
3759                 ASSERT(fs_info->scrub_workers == NULL);
3760                 fs_info->scrub_workers = btrfs_alloc_workqueue(fs_info, "scrub",
3761                                 flags, is_dev_replace ? 1 : max_active, 4);
3762                 if (!fs_info->scrub_workers)
3763                         goto fail_scrub_workers;
3764
3765                 ASSERT(fs_info->scrub_wr_completion_workers == NULL);
3766                 fs_info->scrub_wr_completion_workers =
3767                         btrfs_alloc_workqueue(fs_info, "scrubwrc", flags,
3768                                               max_active, 2);
3769                 if (!fs_info->scrub_wr_completion_workers)
3770                         goto fail_scrub_wr_completion_workers;
3771
3772                 ASSERT(fs_info->scrub_parity_workers == NULL);
3773                 fs_info->scrub_parity_workers =
3774                         btrfs_alloc_workqueue(fs_info, "scrubparity", flags,
3775                                               max_active, 2);
3776                 if (!fs_info->scrub_parity_workers)
3777                         goto fail_scrub_parity_workers;
3778
3779                 refcount_set(&fs_info->scrub_workers_refcnt, 1);
3780         } else {
3781                 refcount_inc(&fs_info->scrub_workers_refcnt);
3782         }
3783         return 0;
3784
3785 fail_scrub_parity_workers:
3786         btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers);
3787 fail_scrub_wr_completion_workers:
3788         btrfs_destroy_workqueue(fs_info->scrub_workers);
3789 fail_scrub_workers:
3790         return -ENOMEM;
3791 }
3792
3793 int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
3794                     u64 end, struct btrfs_scrub_progress *progress,
3795                     int readonly, int is_dev_replace)
3796 {
3797         struct scrub_ctx *sctx;
3798         int ret;
3799         struct btrfs_device *dev;
3800         unsigned int nofs_flag;
3801         struct btrfs_workqueue *scrub_workers = NULL;
3802         struct btrfs_workqueue *scrub_wr_comp = NULL;
3803         struct btrfs_workqueue *scrub_parity = NULL;
3804
3805         if (btrfs_fs_closing(fs_info))
3806                 return -EAGAIN;
3807
3808         if (fs_info->nodesize > BTRFS_STRIPE_LEN) {
3809                 /*
3810                  * in this case scrub is unable to calculate the checksum
3811                  * the way scrub is implemented. Do not handle this
3812                  * situation at all because it won't ever happen.
3813                  */
3814                 btrfs_err(fs_info,
3815                            "scrub: size assumption nodesize <= BTRFS_STRIPE_LEN (%d <= %d) fails",
3816                        fs_info->nodesize,
3817                        BTRFS_STRIPE_LEN);
3818                 return -EINVAL;
3819         }
3820
3821         if (fs_info->sectorsize != PAGE_SIZE) {
3822                 /* not supported for data w/o checksums */
3823                 btrfs_err_rl(fs_info,
3824                            "scrub: size assumption sectorsize != PAGE_SIZE (%d != %lu) fails",
3825                        fs_info->sectorsize, PAGE_SIZE);
3826                 return -EINVAL;
3827         }
3828
3829         if (fs_info->nodesize >
3830             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK ||
3831             fs_info->sectorsize > PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK) {
3832                 /*
3833                  * would exhaust the array bounds of pagev member in
3834                  * struct scrub_block
3835                  */
3836                 btrfs_err(fs_info,
3837                           "scrub: size assumption nodesize and sectorsize <= SCRUB_MAX_PAGES_PER_BLOCK (%d <= %d && %d <= %d) fails",
3838                        fs_info->nodesize,
3839                        SCRUB_MAX_PAGES_PER_BLOCK,
3840                        fs_info->sectorsize,
3841                        SCRUB_MAX_PAGES_PER_BLOCK);
3842                 return -EINVAL;
3843         }
3844
3845         /* Allocate outside of device_list_mutex */
3846         sctx = scrub_setup_ctx(fs_info, is_dev_replace);
3847         if (IS_ERR(sctx))
3848                 return PTR_ERR(sctx);
3849
3850         mutex_lock(&fs_info->fs_devices->device_list_mutex);
3851         dev = btrfs_find_device(fs_info->fs_devices, devid, NULL, NULL, true);
3852         if (!dev || (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state) &&
3853                      !is_dev_replace)) {
3854                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3855                 ret = -ENODEV;
3856                 goto out_free_ctx;
3857         }
3858
3859         if (!is_dev_replace && !readonly &&
3860             !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state)) {
3861                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3862                 btrfs_err_in_rcu(fs_info, "scrub: device %s is not writable",
3863                                 rcu_str_deref(dev->name));
3864                 ret = -EROFS;
3865                 goto out_free_ctx;
3866         }
3867
3868         mutex_lock(&fs_info->scrub_lock);
3869         if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &dev->dev_state) ||
3870             test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &dev->dev_state)) {
3871                 mutex_unlock(&fs_info->scrub_lock);
3872                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3873                 ret = -EIO;
3874                 goto out_free_ctx;
3875         }
3876
3877         down_read(&fs_info->dev_replace.rwsem);
3878         if (dev->scrub_ctx ||
3879             (!is_dev_replace &&
3880              btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) {
3881                 up_read(&fs_info->dev_replace.rwsem);
3882                 mutex_unlock(&fs_info->scrub_lock);
3883                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3884                 ret = -EINPROGRESS;
3885                 goto out_free_ctx;
3886         }
3887         up_read(&fs_info->dev_replace.rwsem);
3888
3889         ret = scrub_workers_get(fs_info, is_dev_replace);
3890         if (ret) {
3891                 mutex_unlock(&fs_info->scrub_lock);
3892                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3893                 goto out_free_ctx;
3894         }
3895
3896         sctx->readonly = readonly;
3897         dev->scrub_ctx = sctx;
3898         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3899
3900         /*
3901          * checking @scrub_pause_req here, we can avoid
3902          * race between committing transaction and scrubbing.
3903          */
3904         __scrub_blocked_if_needed(fs_info);
3905         atomic_inc(&fs_info->scrubs_running);
3906         mutex_unlock(&fs_info->scrub_lock);
3907
3908         /*
3909          * In order to avoid deadlock with reclaim when there is a transaction
3910          * trying to pause scrub, make sure we use GFP_NOFS for all the
3911          * allocations done at btrfs_scrub_pages() and scrub_pages_for_parity()
3912          * invoked by our callees. The pausing request is done when the
3913          * transaction commit starts, and it blocks the transaction until scrub
3914          * is paused (done at specific points at scrub_stripe() or right above
3915          * before incrementing fs_info->scrubs_running).
3916          */
3917         nofs_flag = memalloc_nofs_save();
3918         if (!is_dev_replace) {
3919                 btrfs_info(fs_info, "scrub: started on devid %llu", devid);
3920                 /*
3921                  * by holding device list mutex, we can
3922                  * kick off writing super in log tree sync.
3923                  */
3924                 mutex_lock(&fs_info->fs_devices->device_list_mutex);
3925                 ret = scrub_supers(sctx, dev);
3926                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3927         }
3928
3929         if (!ret)
3930                 ret = scrub_enumerate_chunks(sctx, dev, start, end);
3931         memalloc_nofs_restore(nofs_flag);
3932
3933         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
3934         atomic_dec(&fs_info->scrubs_running);
3935         wake_up(&fs_info->scrub_pause_wait);
3936
3937         wait_event(sctx->list_wait, atomic_read(&sctx->workers_pending) == 0);
3938
3939         if (progress)
3940                 memcpy(progress, &sctx->stat, sizeof(*progress));
3941
3942         if (!is_dev_replace)
3943                 btrfs_info(fs_info, "scrub: %s on devid %llu with status: %d",
3944                         ret ? "not finished" : "finished", devid, ret);
3945
3946         mutex_lock(&fs_info->scrub_lock);
3947         dev->scrub_ctx = NULL;
3948         if (refcount_dec_and_test(&fs_info->scrub_workers_refcnt)) {
3949                 scrub_workers = fs_info->scrub_workers;
3950                 scrub_wr_comp = fs_info->scrub_wr_completion_workers;
3951                 scrub_parity = fs_info->scrub_parity_workers;
3952
3953                 fs_info->scrub_workers = NULL;
3954                 fs_info->scrub_wr_completion_workers = NULL;
3955                 fs_info->scrub_parity_workers = NULL;
3956         }
3957         mutex_unlock(&fs_info->scrub_lock);
3958
3959         btrfs_destroy_workqueue(scrub_workers);
3960         btrfs_destroy_workqueue(scrub_wr_comp);
3961         btrfs_destroy_workqueue(scrub_parity);
3962         scrub_put_ctx(sctx);
3963
3964         return ret;
3965
3966 out_free_ctx:
3967         scrub_free_ctx(sctx);
3968
3969         return ret;
3970 }
3971
3972 void btrfs_scrub_pause(struct btrfs_fs_info *fs_info)
3973 {
3974         mutex_lock(&fs_info->scrub_lock);
3975         atomic_inc(&fs_info->scrub_pause_req);
3976         while (atomic_read(&fs_info->scrubs_paused) !=
3977                atomic_read(&fs_info->scrubs_running)) {
3978                 mutex_unlock(&fs_info->scrub_lock);
3979                 wait_event(fs_info->scrub_pause_wait,
3980                            atomic_read(&fs_info->scrubs_paused) ==
3981                            atomic_read(&fs_info->scrubs_running));
3982                 mutex_lock(&fs_info->scrub_lock);
3983         }
3984         mutex_unlock(&fs_info->scrub_lock);
3985 }
3986
3987 void btrfs_scrub_continue(struct btrfs_fs_info *fs_info)
3988 {
3989         atomic_dec(&fs_info->scrub_pause_req);
3990         wake_up(&fs_info->scrub_pause_wait);
3991 }
3992
3993 int btrfs_scrub_cancel(struct btrfs_fs_info *fs_info)
3994 {
3995         mutex_lock(&fs_info->scrub_lock);
3996         if (!atomic_read(&fs_info->scrubs_running)) {
3997                 mutex_unlock(&fs_info->scrub_lock);
3998                 return -ENOTCONN;
3999         }
4000
4001         atomic_inc(&fs_info->scrub_cancel_req);
4002         while (atomic_read(&fs_info->scrubs_running)) {
4003                 mutex_unlock(&fs_info->scrub_lock);
4004                 wait_event(fs_info->scrub_pause_wait,
4005                            atomic_read(&fs_info->scrubs_running) == 0);
4006                 mutex_lock(&fs_info->scrub_lock);
4007         }
4008         atomic_dec(&fs_info->scrub_cancel_req);
4009         mutex_unlock(&fs_info->scrub_lock);
4010
4011         return 0;
4012 }
4013
4014 int btrfs_scrub_cancel_dev(struct btrfs_device *dev)
4015 {
4016         struct btrfs_fs_info *fs_info = dev->fs_info;
4017         struct scrub_ctx *sctx;
4018
4019         mutex_lock(&fs_info->scrub_lock);
4020         sctx = dev->scrub_ctx;
4021         if (!sctx) {
4022                 mutex_unlock(&fs_info->scrub_lock);
4023                 return -ENOTCONN;
4024         }
4025         atomic_inc(&sctx->cancel_req);
4026         while (dev->scrub_ctx) {
4027                 mutex_unlock(&fs_info->scrub_lock);
4028                 wait_event(fs_info->scrub_pause_wait,
4029                            dev->scrub_ctx == NULL);
4030                 mutex_lock(&fs_info->scrub_lock);
4031         }
4032         mutex_unlock(&fs_info->scrub_lock);
4033
4034         return 0;
4035 }
4036
4037 int btrfs_scrub_progress(struct btrfs_fs_info *fs_info, u64 devid,
4038                          struct btrfs_scrub_progress *progress)
4039 {
4040         struct btrfs_device *dev;
4041         struct scrub_ctx *sctx = NULL;
4042
4043         mutex_lock(&fs_info->fs_devices->device_list_mutex);
4044         dev = btrfs_find_device(fs_info->fs_devices, devid, NULL, NULL, true);
4045         if (dev)
4046                 sctx = dev->scrub_ctx;
4047         if (sctx)
4048                 memcpy(progress, &sctx->stat, sizeof(*progress));
4049         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
4050
4051         return dev ? (sctx ? 0 : -ENOTCONN) : -ENODEV;
4052 }
4053
4054 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
4055                                u64 extent_logical, u64 extent_len,
4056                                u64 *extent_physical,
4057                                struct btrfs_device **extent_dev,
4058                                int *extent_mirror_num)
4059 {
4060         u64 mapped_length;
4061         struct btrfs_bio *bbio = NULL;
4062         int ret;
4063
4064         mapped_length = extent_len;
4065         ret = btrfs_map_block(fs_info, BTRFS_MAP_READ, extent_logical,
4066                               &mapped_length, &bbio, 0);
4067         if (ret || !bbio || mapped_length < extent_len ||
4068             !bbio->stripes[0].dev->bdev) {
4069                 btrfs_put_bbio(bbio);
4070                 return;
4071         }
4072
4073         *extent_physical = bbio->stripes[0].physical;
4074         *extent_mirror_num = bbio->mirror_num;
4075         *extent_dev = bbio->stripes[0].dev;
4076         btrfs_put_bbio(bbio);
4077 }